COBOL - Overview
GO TO LINK & DOWNLOAD:COBOL_EBOOK_PDF
Introduction to COBOL
COBOL is a high-level language. One must understand the way COBOL works. Computers only understand machine code, a binary stream of 0s and 1s. COBOL code must be converted into machine code using a compiler. Run the program source through a compiler. The compiler first checks for any syntax errors and then converts it into machine language. The compiler creates a output file which is known as load module. This output file contains executable code in the form of 0s and 1s.
Evolution of COBOL
During 1950s, when the businesses were growing in the western part of the world, there was a need to automate various processes for ease of operation and this gave birth to a high-level programming language meant for business data processing.
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In 1959, COBOL was developed by CODASYL (Conference on Data Systems Language).
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The next version, COBOL-61, was released in 1961 with some revisions.
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In 1968, COBOL was approved by ANSI as a standard language for commercial use (COBOL-68).
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It was again revised in 1974 and 1985 to develop subsequent versions named COBOL-74 and COBOL-85 respectively.
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In 2002, Object-Oriented COBOL was released, which could use encapsulated objects as a normal part of COBOL programming.
Importance of COBOL
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COBOL was the first widely used high-level programming language. It is an English-like language which is user friendly. All the instructions can be coded in simple English words.
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COBOL is also used as a self-documenting language.
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COBOL can handle huge data processing.
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COBOL is compatible with its previous versions.
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COBOL has effective error messages and so, resolution of bugs is easier.
Features of COBOL
Standard Language
COBOL is a standard language that can be compiled and executed on machines such as IBM AS/400, personal computers, etc.
Business Oriented
COBOL was designed for business-oriented applications related to financial domain, defense domain, etc. It can handle huge volumes of data because of its advanced file handling capabilities.
Robust Language
COBOL is a robust language as its numerous debugging and testing tools are available for almost all computer platforms.
Structured Language
Logical control structures are available in COBOL which makes it easier to read and modify. COBOL has different divisions, so it is easy to debug.
COBOL - Environment Setup
Installing COBOL on Windows/Linux
There are many Free Mainframe Emulators available for Windows which can be used to write and learn simple COBOL programs.
One such emulator is Hercules, which can be easily installed on Windows by following a few simple steps as given below:
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Download and install the Hercules emulator, which is available from the Hercules' home site: www.hercules-390.eu
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Once you have installed the package on Windows machine, it will create a folder like C:/hercules/mvs/cobol.
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Run the Command Prompt (CMD) and reach the directory C:/hercules/mvs/cobol on CMD.
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The complete guide on various commands to write and execute a JCL and COBOL programs can be found at:
www.jaymoseley.com/hercules/installmvs/instmvs2.htm
Hercules is an open-source software implementation of the mainframe System/370 and ESA/390 architectures, in addition to the latest 64-bit z/Architecture. Hercules runs under Linux, Windows, Solaris, FreeBSD, and Mac OS X.
A user can connect to a mainframe server in a number of ways such a thin client, dummy terminal, Virtual Client System (VCS), or Virtual Desktop System (VDS). Every valid user is given a login id to enter into the Z/OS interface (TSO/E or ISPF).
Compiling COBOL Programs
In order to execute a COBOL program in batch mode using JCL, the program needs to be compiled, and a load module is created with all the sub-programs. The JCL uses the load module and not the actual program at the time of execution. The load libraries are concatenated and given to the JCL at the time of execution using JCLLIB or STEPLIB.
There are many mainframe compiler utilities available to compile a COBOL program. Some corporate companies use Change Management tools like Endevor, which compiles and stores every version of the program. This is useful in tracking the changes made to the program.
//COMPILE JOB ,CLASS=6,MSGCLASS=X,NOTIFY=&SYSUID
//*
//STEP1 EXEC IGYCRCTL,PARM=RMODE,DYNAM,SSRANGE
//SYSIN DD DSN=MYDATA.URMI.SOURCES(MYCOBB),DISP=SHR
//SYSLIB DD DSN=MYDATA.URMI.COPYBOOK(MYCOPY),DISP=SHR
//SYSLMOD DD DSN=MYDATA.URMI.LOAD(MYCOBB),DISP=SHR
//SYSPRINT DD SYSOUT=*
//*
IGYCRCTL is an IBM COBOL compiler utility. The compiler options are passed using the PARM parameter. In the above example, RMODE instructs the compiler to use relative addressing mode in the program. The COBOL program is passed using the SYSIN parameter. Copybook is the library used by the program in SYSLIB.
Executing COBOL Programs
Give below is a JCL example where the program MYPROG is executed using the input file MYDATA.URMI.INPUT and produces two output files written to the spool.
//COBBSTEP JOB CLASS=6,NOTIFY=&SYSUID
//
//STEP10 EXEC PGM=MYPROG,PARM=ACCT5000
//STEPLIB DD DSN=MYDATA.URMI.LOADLIB,DISP=SHR
//INPUT1 DD DSN=MYDATA.URMI.INPUT,DISP=SHR
//OUT1 DD SYSOUT=*
//OUT2 DD SYSOUT=*
//SYSIN DD *
//CUST1 1000
//CUST2 1001
/*
The load module of MYPROG is located in MYDATA.URMI.LOADLIB. This is important to note that the above JCL can be used for a non-DB2 COBOL module only.
Executing COBOL-DB2 programs
For running a COBOL-DB2 program, a specialized IBM utility is used in the JCL and the program; DB2 region and required parameters are passed as input to the utility.
The steps followed in running a COBOL-DB2 program are as follows:
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When a COBOL-DB2 program is compiled, a DBRM (Database Request Module) is created along with the load module. The DBRM contains the SQL statements of the COBOL programs with its syntax checked to be correct.
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The DBRM is bound to the DB2 region (environment) in which the COBOL will run. This can be done using the IKJEFT01 utility in a JCL.
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After the bind step, the COBOL-DB2 program is run using IKJEFT01 (again) with the load library and the DBRM library as the input to the JCL.
//STEP001 EXEC PGM=IKJEFT01
//*
//STEPLIB DD DSN=MYDATA.URMI.DBRMLIB,DISP=SHR
//*
//input files
//output files
//SYSPRINT DD SYSOUT=*
//SYSABOUT DD SYSOUT=*
//SYSDBOUT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//DISPLAY DD SYSOUT=*
//SYSOUT DD SYSOUT=*
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
DSN SYSTEM(SSID)
RUN PROGRAM(MYCOBB) PLAN(PLANNAME) PARM(parameters to cobol program) -
LIB('MYDATA.URMI.LOADLIB')
END
/*
In the above example, MYCOBB is the COBOL-DB2 program run using IKJEFT01. Please note that the program name, DB2 Sub-System Id (SSID), and DB2 Plan name are passed within the SYSTSIN DD statement. The DBRM library is specified in the STEPLIB.
Try it Option Online
You really do not need to set up your own environment to start learning COBOL programming language. Reason is very simple, we have already set up COBOL Programming environment online, so that you can compile and execute all the available examples online at the same time when you are doing your theory work. This gives you confidence in what you are reading and to check the result with different options. Feel free to modify any example and execute it online.
Try the following example using our Try it option available alongside the code in our website.
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
PROCEDURE DIVISION.
DISPLAY 'Hello World'.
STOP RUN.
When you compile and execute the above program, it produces the following result:
Hello World
For some of the examples given in this tutorial, you will find a Try it option in our website code selections at the to right corner that will take you to the online compiler. So just make use of it and enjoy your learning. Try it option would work only with the code compatible with OpenCOBOL. The programs that require JCL (Input file, Output file or Parameters) for execution would not run on Tryit option.
COBOL - Program Structure
A COBOL program structure consists of divisions as shown in the following image:
A brief introduction of these divisions is given below:
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Sections are the logical subdivision of program logic. A section is a collection of paragraphs.
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Paragraphs are the subdivision of a section or division. It is either user-defined or a predefined name followed by a period, and consists of zero or more sentences/entries.
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Sentences are the combination of one or more statements. Sentences appear only in the Procedure division. A sentence must end with a period.
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Statements are meaningful COBOL statement that performs some processing.
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Characters are the lowest in the hierarchy and cannot be divisible.
You can co-relate the above-mentioned terms with the COBOL program in the following example:
PROCEDURE DIVISION.
A0000-FIRST-PARA SECTION.
FIRST-PARAGRAPH.
ACCEPT WS-ID - Statement-1 -----|
MOVE '10' TO WS-ID - Statement-2 |-- Sentence - 1
DISPLAY WS-ID - Statement-3 -----|
.
Divisions
COBOL program consists of four divisions.
Identification Division
It is the first and only mandatory division of every COBOL program. The programmer and the compiler use this division to identify the program. In this Division, PROGRAM-ID is the only mandatory paragraph. PROGRAM-ID specifies the program name that can consist 1 to 30 characters.
Try the following example using the Try it option online.
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
PROCEDURE DIVISION.
DISPLAY 'Welcome to Tutorialspoint'.
STOP RUN.
Given below is the JCL to execute the above COBOL program.
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
Welcome to Tutorialspoint
Environment Division
Environment division is used to specify input and output files to the program. It consists of two sections:
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Configuration section provides information about the system on which the program is written and executed. It consists of two paragraphs:
Source computer : System used to compile the program.
Object computer : System used to execute the program.
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Input-Output section provides information about the files to be used in the program. It consists of two paragraphs:
File control : Provides information of external data sets used in the program.
I-O control : Provides information of files used in the program.
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
SOURCE-COMPUTER. XXX-ZOS.
OBJECT-COMPUTER. XXX-ZOS.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT FILEN ASSIGN TO DDNAME
ORGANIZATION IS SEQUENTIAL.
Data Division
Data division is used to define the variables used in the program. It consists of four sections:
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File section is used to define the record structure of the file.
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Working-Storage section is used to declare temporary variables and file structures which are used in the program.
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Local-Storage section is similar to Working-Storage section. The only difference is that the variables will be allocated and initialized every time program a starts execution.
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Linkage section is used to describe the data names that are received from an external program.
COBOL Program
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT FILEN ASSIGN TO INPUT.
ORGANIZATION IS SEQUENTIAL.
ACCESS IS SEQUENTIAL.
DATA DIVISION.
FILE SECTION.
FD FILEN
01 NAME PIC A(25).
WORKING-STORAGE SECTION.
01 WS-STUDENT PIC A(30).
01 WS-ID PIC 9(5).
LOCAL-STORAGE SECTION.
01 LS-CLASS PIC 9(3).
LINKAGE SECTION.
01 LS-ID PIC 9(5).
PROCEDURE DIVISION.
DISPLAY 'Executing COBOL program using JCL'.
STOP RUN.
The JCL to execute the above COBOL program is as follows:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
//INPUT DD DSN=ABC.EFG.XYZ,DISP=SHR
When you compile and execute the above program, it produces the following result:
Executing COBOL program using JCL
Procedure Division
Procedure division is used to include the logic of the program. It consists of executable statements using variables defined in the data division. In this division, paragraph and section names are user-defined.
There must be at least one statement in the procedure division. The last statement to end the execution in this division is either STOP RUN which is used in the calling programs or EXIT PROGRAM which is used in the called programs.
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NAME PIC A(30).
01 WS-ID PIC 9(5) VALUE '12345'.
PROCEDURE DIVISION.
A000-FIRST-PARA.
DISPLAY 'Hello World'.
MOVE 'TutorialsPoint' TO WS-NAME.
DISPLAY "My name is : "WS-NAME.
DISPLAY "My ID is : "WS-ID.
STOP RUN.
JCL to execute the above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
Hello World
My name is : TutorialsPoint
My ID is : 12345
COBOL - Basic Syntax
Character Set
'Characters' are lowest in the hierarchy and they cannot be divided further. The COBOL Character Set includes 78 characters which are shown below:
Character Description A-Z Alphabets(Upper Case) a-z Alphabets (Lower Case) 0-9 Numeric Space + Plus Sign - Minus Sign or Hyphen * Asterisk / Forward Slash $ Currency Sign , Comma ; Semicolon . Decimal Point or Period " Quotation Marks ( Left Parenthesis ) Right Parenthesis > Greater than < Less than : Colon ' Apostrophe = Equal Sign
Coding Sheet
The source program of COBOL must be written in a format acceptable to the compilers. COBOL programs are written on COBOL coding sheets. There are 80 characters position on each line of a coding sheet.
Character positions are grouped into the following five fields:
Positions Field Description 1-6 Column Numbers Reserved for line numbers. 7 Indicator It can have Asterisk (*) indicating comments, Hyphen (-) indicating continuation and Slash ( / ) indicating form feed. 8-11 Area A All COBOL divisions, sections, paragraphs and some special entries must begin in Area A. 12-72 Area B All COBOL statements must begin in area B. 73-80 Identification Area It can be used as needed by the programmer.
Example
The following example shows a COBOL coding sheet:
000100 IDENTIFICATION DIVISION. 000100
000200 PROGRAM-ID. HELLO. 000101
000250* THIS IS A COMMENT LINE 000102
000300 PROCEDURE DIVISION. 000103
000350 A000-FIRST-PARA. 000104
000400 DISPLAY “Coding Sheet”. 000105
000500 STOP RUN. 000106
JCL to execute the above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
Coding Sheet
Character Strings
Character strings are formed by combining individual characters. A character string can be a
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Comment,
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Literal, or
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COBOL word.
All character strings must be ended with separators. A separator is used to separate character strings.
Frequently used separators : Space, Comma, Period, Apostrophe, Left/Right Parenthesis, and Quotation mark.
Comment
A comment is a character string that does not affect the execution of a program. It can be any combination of characters.
There are two types of comments:
Comment Line
Comment line can be written in any column. The compiler does not check a comment line for syntax and treats it for documentation.
Comment Entry
Comment entries are those that are included in the optional paragraphs of an Identification Division. They are written in Area B and programmers use it for reference.
The text highlighted in Bold are the commented entries in the following example:
000100 IDENTIFICATION DIVISION. 000100
000150 PROGRAM-ID. HELLO. 000101
000200 AUTHOR. TUTORIALSPOINT. 000102
000250* THIS IS A COMMENT LINE 000103
000300 PROCEDURE DIVISION. 000104
000350 A000-FIRST-PARA. 000105
000360/ First Para Begins - Documentation Purpose 000106
000400 DISPLAY “Comment line”. 000107
000500 STOP RUN. 000108
JCL to execute above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
Comment Line
Literal
Literal is a constant that is directly hard coded in a program. In the following example, "Hello World" is a literal.
PROCEDURE DIVISION.
DISPLAY 'Hello World'.
There are two types of literals as discussed below:
Alphanumeric Literal
Alphanumeric Literals are enclosed in quotes or apostrophe. Length can be up to 160 characters. An apostrophe or a quote can be a part of a literal only if it is paired. Starting and ending of the literal should be same, either apostrophe or quote.
Example
The following example shows valid and invalid Alphanumeric Literals:
Valid:
‘This is valid’
"This is valid"
‘This isn’’t invalid’
Invalid:
‘This is invalid”
‘This isn’t valid’
Numeric Literal
A Numeric Literal is a combination of digits from 0 to 9, +, -, or decimal point. Length can be up to 18 characters. Sign cannot be the rightmost character. Decimal point should not appear at the end.
Example
The following example shows valid and invalid Numeric Literals:
Valid:
100
+10.9
-1.9
Invalid:
1,00
10.
10.9-
COBOL Word
COBOL Word is a character string that can be a reserved word or a user-defined word. Length can be up to 30 characters.
User-Defined
User-defined words are used for naming files, data, records, paragraph names and sections. Alphabets, digits, and hyphens are allowed while forming user-defined words. You cannot use COBOL reserved words.
Reserved Words
Reserved words are predefined words in COBOL. Different types of reserved words that we use frequently are as follows:
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Keywords like ADD, ACCEPT, MOVE, etc.
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Special characters words like +, -, *, <, <=, etc
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Figurative constants are constant values like ZERO, SPACES, etc. All the constant values of figurative constants are mentioned in the following table:
Figurative Constants
Figurative Constants Description HIGH-VALUES One or more characters which will be at the highest position in descending order. LOW-VALUES One or more characters have zeros in binary representation. ZERO/ZEROES One or more zero depending on the size of the variable. SPACES One or more spaces. QUOTES Single or double quotes. ALL literal Fills the data-item with Literal.
COBOL - Data Types
Data Division is used to define the variables used in a program. To describe data in COBOL, one must understand the following terms:
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Data Name
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Level Number
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Picture Clause
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Value Clause
01 TOTAL-STUDENTS PIC9(5) VALUE '125'.
| | | |
| | | |
| | | |
Level Number Data Name Picture Clause Value Clause
Data Name
Data names must be defined in the Data Division before using them in the Procedure Division. They must have a user-defined name; reserved words cannot be used. Data names gives reference to the memory locations where actual data is stored. They can be elementary or group type.
Example
The following example shows valid and invalid data names:
Valid:
WS-NAME
TOTAL-STUDENTS
A100
100B
Invalid:
MOVE (Reserved Words)
COMPUTE (Reserved Words)
100 (No Alphabet)
100+B (+ is not allowed)
Level Number
Level number is used to specify the level of data in a record. They are used to differentiate between elementary items and group items. Elementary items can be grouped together to create group items.
Level Number Description 01 Record description entry 02 to 49 Group and Elementary items 66 Rename Clause items 77 Items which cannot be sub-divided 88 Condition name entry
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Elementary items cannot be divided further. Level number, Data name, Picture clause and Value clause (optional) are used to describe an elementary item.
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Group items consist of one or more elementary items. Level number, Data name, and Value clause (optional) are used to describe a group item. Group level number is always 01.
Example
The following example shows Group and Elementary items:
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NAME PIC X(25). ---> ELEMENTARY ITEM
01 WS-CLASS PIC 9(2) VALUE '10'. ---> ELEMENTARY ITEM
01 WS-ADDRESS. ---> GROUP ITEM
05 WS-HOUSE-NUMBER PIC 9(3). ---> ELEMENTARY ITEM
05 WS-STREET PIC X(15). ---> ELEMENTARY ITEM
05 WS-CITY PIC X(15). ---> ELEMENTARY ITEM
05 WS-COUNTRY PIC X(15) VALUE 'INDIA'. ---> ELEMENTARY ITEM
Picture Clause
Picture clause is used to define the following items:
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Data type can be numeric, alphabetic, or alphanumeric. Numeric type consists of only digits 0 to 9. Alphabetic type consists of letters A to Z and spaces. Alphanumeric type consists of digits, letters, and special characters.
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Sign can be used with numeric data. It can be either + or .
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Decimal point position can be used with numeric data. Assumed position is the position of decimal point and not included in the data.
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Length defines the number of bytes used by the data item.
Symbols used in a Picture clause:
Symbol Description 9 Numeric A Alphabetic X Alphanumeric V Implicit Decimal S Sign P Assumed Decimal
Example
The following example shows the use of PIC clause:
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NUM1 PIC S9(3)V9(2).
01 WS-NUM2 PIC PPP999.
01 WS-NUM3 PIC S9(3)V9(2) VALUE -123.45.
01 WS-NAME PIC A(6) VALUE 'ABCDEF'.
01 WS-ID PIC X(5) VALUE 'A121$'.
PROCEDURE DIVISION.
DISPLAY "WS-NUM1 : "WS-NUM1.
DISPLAY "WS-NUM2 : "WS-NUM2.
DISPLAY "WS-NUM3 : "WS-NUM3.
DISPLAY "WS-NAME : "WS-NAME.
DISPLAY "WS-ID : "WS-ID.
STOP RUN.
JCL to execute the above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
WS-NUM1 : +000.00
WS-NUM2 : .000000
WS-NUM3 : -123.45
WS-NAME : ABCDEF
WS-ID : A121$
Value Clause
Value clause is an optional clause which is used to initialize the data items. The values can be numeric literal, alphanumeric literal, or figurative constant. It can be used with both group and elementary items.
Example
The following example shows the use of VALUE clause:
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NUM1 PIC 99V9 VALUE IS 3.5.
01 WS-NAME PIC A(6) VALUE 'ABCD'.
01 WS-ID PIC 99 VALUE ZERO.
PROCEDURE DIVISION.
DISPLAY "WS-NUM1 : "WS-NUM1.
DISPLAY "WS-NAME : "WS-NAME.
DISPLAY "WS-ID : "WS-ID.
STOP RUN.
JCL to execute the above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
WS-NUM1 : 03.5
WS-NAME : ABCD
WS-ID : 00
COBOL - Basic Verbs
COBOL verbs are used in the procedure division for data processing. A statement always start with a COBOL verb. There are several COBOL verbs with different types of actions.
Input / Output Verbs
Input/Output verbs are used to get data from the user and display the output of COBOL programs. The following two verbs are used for this process:
Accept Verb
Accept verb is used to get data such as date, time, and day from the operating system or directly the from user. If a program is accepting data from the user, then it needs to be passed through JCL. While getting data from the operating system FROM option is included as shown in the following below example:
ACCEPT WS-STUDENT-NAME.
ACCEPT WS-DATE FROM SYSTEM-DATE.
Display Verb
Display verb is used to display the output of a COBOL program.
DISPLAY WS-STUDENT-NAME.
DISPLAY "System date is : " WS-DATE.
COBOL PROGRAM
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-STUDENT-NAME PIC X(25).
01 WS-DATE PIC X(10).
PROCEDURE DIVISION.
ACCEPT WS-STUDENT_NAME.
ACCEPT WS-DATE FROM DATE.
DISPLAY "Name : " WS-STUDENT_NAME.
DISPLAY "Date : " WS-DATE.
STOP RUN.
JCL to execute the above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
//INPUT DD DSN=PROGRAM.DIRECTORY,DISP=SHR
//SYSIN DD *
TutorialsPoint
/*
When you compile and execute the above program, it produces the following result:
Name : TutorialsPoint
Date : 2014-08-30
Initialize Verb
Initialize verb is used to initialize a group item or an elementary item. Data names with RENAME clause cannot be initialized. Numeric data items are replaced by ZEROES. Alphanumeric or alphabetic data items are replaced by SPACES. If we include REPLACING term, then data items can be initialized to the given replacing value as shown in the following example:
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NAME PIC A(30) VALUE 'ABCDEF'.
01 WS-ID PIC 9(5).
01 WS-ADDRESS.
05 WS-HOUSE-NUMBER PIC 9(3).
05 WS-COUNTRY PIC X(15).
05 WS-PINCODE PIC 9(6) VALUE 123456.
PROCEDURE DIVISION.
A000-FIRST-PARA.
INITIALIZE WS-NAME, WS-ADDRESS.
INITIALIZE WS-ID REPLACING NUMERIC DATA BY 12345.
DISPLAY "My name is : "WS-NAME.
DISPLAY "My ID is : "WS-ID.
DISPLAY "Address : "WS-ADDRESS.
DISPLAY "House Number : "WS-HOUSE-NUMBER.
DISPLAY "Country : "WS-COUNTRY.
DISPLAY "Pincode : "WS-PINCODE.
STOP RUN.
JCL to execute the above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
My name is :
My ID is : 12345
Address : 000 000000
House Number : 000
Country :
Pincode : 000000
Move Verb
Move verb is used to copy data from source data to destination data. It can be used on both elementary and group data items. For group data items, MOVE CORRESPONDING/CORR is used. In try it option, MOVE CORR is not working; but on a mainframe server it will work.
For moving data from a string, MOVE(x:l) is used where x is the starting position and l is the length. Data will be truncated if destination data item PIC clause is less than the source data item PIC clause. If the destination data item PIC clause is more than the source data item PIC clause, then ZEROS or SPACES will be added in the extra bytes. The following example makes it clear:
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NUM1 PIC 9(9).
01 WS-NUM2 PIC 9(9).
01 WS-NUM3 PIC 9(5).
01 WS-NUM4 PIC 9(6).
01 WS-ADDRESS.
05 WS-HOUSE-NUMBER PIC 9(3).
05 WS-COUNTRY PIC X(5).
05 WS-PINCODE PIC 9(6).
01 WS-ADDRESS1.
05 WS-HOUSE-NUMBER1 PIC 9(3).
05 WS-COUNTRY1 PIC X(5).
05 WS-PINCODE1 PIC 9(6).
PROCEDURE DIVISION.
A000-FIRST-PARA.
MOVE 123456789 TO WS-NUM1.
MOVE WS-NUM1 TO WS-NUM2 WS-NUM3.
MOVE WS-NUM1(3:6) TO WS-NUM4.
MOVE 123 TO WS-HOUSE-NUMBER.
MOVE 'INDIA' TO WS-COUNTRY.
MOVE 112233 TO WS-PINCODE.
MOVE WS-ADDRESS TO WS-ADDRESS1.
DISPLAY "WS-NUM1 : " WS-NUM1
DISPLAY "WS-NUM2 : " WS-NUM2
DISPLAY "WS-NUM3 : " WS-NUM3
DISPLAY "WS-NUM4 : " WS-NUM4
DISPLAY "WS-ADDRESS : " WS-ADDRESS
DISPLAY "WS-ADDRESS1 : " WS-ADDRESS1
STOP RUN.
JCL to execute the above COBOL program.
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program it produces the following result:
WS-NUM1 : 123456789
WS-NUM2 : 123456789
WS-NUM3 : 56789
WS-NUM4 : 345678
WS-ADDRESS : 123INDIA112233
WS-ADDRESS1 : 123INDIA112233
Legal Moves
The following table gives information about the legal moves:
Alphabetic Alphanumeric Numeric Alphabetic Possible Possible Not Possible Alphanumeric Possible Possible Possible Numeric Not Possible Possible Possible
Add Verb
Add verb is used to add two or more numbers and store the result in the destination operand.
Syntax
give below is the syntax to Add two or more numbers:
ADD A B TO C D
ADD A B C TO D GIVING E
ADD CORR WS-GROUP1 TO WS-GROUP2
In syntax-1, A, B, C are added and the result is stored in C (C=A+B+C). A, B, D are added and the result is stored in D (D=A+B+D).
In syntax-2, A, B, C, D are added and the result is stored in E (E=A+B+C+D).
In syntax-3, sub-group items with in WS-GROUP1 and WS GROUP2 are the added and result is stored in WS-GROUP2.
Example
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NUM1 PIC 9(9) VALUE 10 .
01 WS-NUM2 PIC 9(9) VALUE 10.
01 WS-NUM3 PIC 9(9) VALUE 10.
01 WS-NUM4 PIC 9(9) VALUE 10.
01 WS-NUMA PIC 9(9) VALUE 10.
01 WS-NUMB PIC 9(9) VALUE 10.
01 WS-NUMC PIC 9(9) VALUE 10.
01 WS-NUMD PIC 9(9) VALUE 10.
01 WS-NUME PIC 9(9) VALUE 10.
PROCEDURE DIVISION.
ADD WS-NUM1 WS-NUM2 TO WS-NUM3 WS-NUM4.
ADD WS-NUMA WS-NUMB WS-NUMC TO WS-NUMD GIVING WS-NUME.
DISPLAY "WS-NUM1 : " WS-NUM1
DISPLAY "WS-NUM2 : " WS-NUM2
DISPLAY "WS-NUM3 : " WS-NUM3
DISPLAY "WS-NUM4 : " WS-NUM4
DISPLAY "WS-NUMA : " WS-NUMA
DISPLAY "WS-NUMB : " WS-NUMB
DISPLAY "WS-NUMC : " WS-NUMC
DISPLAY "WS-NUMD : " WS-NUMD
DISPLAY "WS-NUME : " WS-NUME
STOP RUN.
JCL to execute the above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
WS-NUM1 : 000000010
WS-NUM2 : 000000010
WS-NUM3 : 000000030
WS-NUM4 : 000000030
WS-NUMA : 000000010
WS-NUMB : 000000010
WS-NUMC : 000000010
WS-NUMD : 000000010
WS-NUME : 000000040
Subtract Verb
Subtract verb is used for subtraction operations.
Syntax
given below is the syntax for Subtract operations:
SUBTRACT A B FROM C D
SUBTRACT A B C FROM D GIVING E
SUBTRACT CORR WS-GROUP1 TO WS-GROUP2
In syntax-1, A and B are added and subtracted from C. The Result is stored in C (C=C-(A+B)). A and B are added and subtracted from D. The result is stored in D (D=D-(A+B)).
In syntax-2, A, B, C are added and subtracted from D. Result is stored in E (E=D-(A+B+C))
In syntax-3, sub-group items within WS-GROUP1 and WS-GROUP2 are subtracted and the result is stored in WS-GROUP2.
Example
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NUM1 PIC 9(9) VALUE 10 .
01 WS-NUM2 PIC 9(9) VALUE 10.
01 WS-NUM3 PIC 9(9) VALUE 100.
01 WS-NUM4 PIC 9(9) VALUE 100.
01 WS-NUMA PIC 9(9) VALUE 10.
01 WS-NUMB PIC 9(9) VALUE 10.
01 WS-NUMC PIC 9(9) VALUE 10.
01 WS-NUMD PIC 9(9) VALUE 100.
01 WS-NUME PIC 9(9) VALUE 10.
PROCEDURE DIVISION.
SUBTRACT WS-NUM1 WS-NUM2 FROM WS-NUM3 WS-NUM4.
SUBTRACT WS-NUMA WS-NUMB WS-NUMC FROM WS-NUMD GIVING WS-NUME.
DISPLAY "WS-NUM1 : " WS-NUM1
DISPLAY "WS-NUM2 : " WS-NUM2
DISPLAY "WS-NUM3 : " WS-NUM3
DISPLAY "WS-NUM4 : " WS-NUM4
DISPLAY "WS-NUMA : " WS-NUMA
DISPLAY "WS-NUMB : " WS-NUMB
DISPLAY "WS-NUMC : " WS-NUMC
DISPLAY "WS-NUMD : " WS-NUMD
DISPLAY "WS-NUME : " WS-NUME
STOP RUN.
JCL to execute the above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
WS-NUM1 : 000000010
WS-NUM2 : 000000010
WS-NUM3 : 000000080
WS-NUM4 : 000000080
WS-NUMA : 000000010
WS-NUMB : 000000010
WS-NUMC : 000000010
WS-NUMD : 000000100
WS-NUME : 000000070
Multiply Verb
Multiply verb is used for multiplication operations.
Syntax
Given below is the syntax to multiply two or more numbers:
MULTIPLY A BY B C
MULTIPLY A BY B GIVING E
In syntax-1, A and B are multipled and the result is stored in B (B=A*B). A and C are multipled and the result is stored in C (C=A*C).
In syntax-2, A and B are multipled and the result is stored in E (E=A*B).
Example
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NUM1 PIC 9(9) VALUE 10 .
01 WS-NUM2 PIC 9(9) VALUE 10.
01 WS-NUM3 PIC 9(9) VALUE 10.
01 WS-NUMA PIC 9(9) VALUE 10.
01 WS-NUMB PIC 9(9) VALUE 10.
01 WS-NUMC PIC 9(9) VALUE 10.
PROCEDURE DIVISION.
MULTIPLY WS-NUM1 BY WS-NUM2 WS-NUM3.
MULTIPLY WS-NUMA BY WS-NUMB GIVING WS-NUMC.
DISPLAY "WS-NUM1 : " WS-NUM1
DISPLAY "WS-NUM2 : " WS-NUM2
DISPLAY "WS-NUM3 : " WS-NUM3
DISPLAY "WS-NUMA : " WS-NUMA
DISPLAY "WS-NUMB : " WS-NUMB
DISPLAY "WS-NUMC : " WS-NUMC
STOP RUN.
JCL to execute the above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
WS-NUM1 : 000000010
WS-NUM2 : 000000100
WS-NUM3 : 000000100
WS-NUMA : 000000010
WS-NUMB : 000000010
WS-NUMC : 000000100
Divide Verb
Divide verb is used for division operations.
Syntax
Given below following is the syntax for division operations:
DIVIDE A INTO B
DIVIDE A BY B GIVING C REMAINDER R
In syntax-1, B is divided by A and the result is stored in B (B=B/A).
In syntax-2, A is divided by B and the result is stored in C (C=A/B) and remainder is stored in R.
Example
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NUM1 PIC 9(9) VALUE 5.
01 WS-NUM2 PIC 9(9) VALUE 250.
01 WS-NUMA PIC 9(9) VALUE 100.
01 WS-NUMB PIC 9(9) VALUE 15.
01 WS-NUMC PIC 9(9).
01 WS-REM PIC 9(9).
PROCEDURE DIVISION.
DIVIDE WS-NUM1 INTO WS-NUM2.
DIVIDE WS-NUMA BY WS-NUMB GIVING WS-NUMC REMAINDER WS-REM.
DISPLAY "WS-NUM1 : " WS-NUM1
DISPLAY "WS-NUM2 : " WS-NUM2
DISPLAY "WS-NUMA : " WS-NUMA
DISPLAY "WS-NUMB : " WS-NUMB
DISPLAY "WS-NUMC : " WS-NUMC
DISPLAY "WS-REM : " WS-REM
STOP RUN.
JCL to execute the above COBOL program:
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
WS-NUM1 : 000000005
WS-NUM2 : 000000050
WS-NUMA : 000000100
WS-NUMB : 000000015
WS-NUMC : 000000006
WS-REM : 000000010
Compute Statement
Compute statement is used to write arithmetic expressions in COBOL. This is a replacement for Add, Subtract, Multiply, and Divide.
Example
IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 WS-NUM1 PIC 9(9) VALUE 10 .
01 WS-NUM2 PIC 9(9) VALUE 10.
01 WS-NUM3 PIC 9(9) VALUE 10.
01 WS-NUMA PIC 9(9) VALUE 50.
01 WS-NUMB PIC 9(9) VALUE 10.
01 WS-NUMC PIC 9(9).
PROCEDURE DIVISION.
COMPUTE WS-NUMC= (WS-NUM1 * WS-NUM2) - (WS-NUMA / WS-NUMB) + WS-NUM3.
DISPLAY "WS-NUM1 : " WS-NUM1
DISPLAY "WS-NUM2 : " WS-NUM2
DISPLAY "WS-NUM3 : " WS-NUM3
DISPLAY "WS-NUMA : " WS-NUMA
DISPLAY "WS-NUMB : " WS-NUMB
DISPLAY "WS-NUMC : " WS-NUMC
STOP RUN.
JCL to execute the above COBOL program.
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C
//STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
WS-NUM1 : 000000010
WS-NUM2 : 000000010
WS-NUM3 : 000000010
WS-NUMA : 000000050
WS-NUMB : 000000010
WS-NUMC : 000000105
In 1959, COBOL was developed by CODASYL (Conference on Data Systems Language).
The next version, COBOL-61, was released in 1961 with some revisions.
In 1968, COBOL was approved by ANSI as a standard language for commercial use (COBOL-68).
It was again revised in 1974 and 1985 to develop subsequent versions named COBOL-74 and COBOL-85 respectively.
In 2002, Object-Oriented COBOL was released, which could use encapsulated objects as a normal part of COBOL programming.
COBOL was the first widely used high-level programming language. It is an English-like language which is user friendly. All the instructions can be coded in simple English words.
COBOL is also used as a self-documenting language.
COBOL can handle huge data processing.
COBOL is compatible with its previous versions.
COBOL has effective error messages and so, resolution of bugs is easier.
Download and install the Hercules emulator, which is available from the Hercules' home site: www.hercules-390.eu
Once you have installed the package on Windows machine, it will create a folder like C:/hercules/mvs/cobol.
Run the Command Prompt (CMD) and reach the directory C:/hercules/mvs/cobol on CMD.
The complete guide on various commands to write and execute a JCL and COBOL programs can be found at:
www.jaymoseley.com/hercules/installmvs/instmvs2.htm
When a COBOL-DB2 program is compiled, a DBRM (Database Request Module) is created along with the load module. The DBRM contains the SQL statements of the COBOL programs with its syntax checked to be correct.
The DBRM is bound to the DB2 region (environment) in which the COBOL will run. This can be done using the IKJEFT01 utility in a JCL.
After the bind step, the COBOL-DB2 program is run using IKJEFT01 (again) with the load library and the DBRM library as the input to the JCL.
Sections are the logical subdivision of program logic. A section is a collection of paragraphs.
Paragraphs are the subdivision of a section or division. It is either user-defined or a predefined name followed by a period, and consists of zero or more sentences/entries.
Sentences are the combination of one or more statements. Sentences appear only in the Procedure division. A sentence must end with a period.
Statements are meaningful COBOL statement that performs some processing.
Characters are the lowest in the hierarchy and cannot be divisible.
Configuration section provides information about the system on which the program is written and executed. It consists of two paragraphs:
Source computer : System used to compile the program.
Object computer : System used to execute the program.
Input-Output section provides information about the files to be used in the program. It consists of two paragraphs:
File control : Provides information of external data sets used in the program.
I-O control : Provides information of files used in the program.
File section is used to define the record structure of the file.
Working-Storage section is used to declare temporary variables and file structures which are used in the program.
Local-Storage section is similar to Working-Storage section. The only difference is that the variables will be allocated and initialized every time program a starts execution.
Linkage section is used to describe the data names that are received from an external program.
Comment,
Literal, or
COBOL word.
Keywords like ADD, ACCEPT, MOVE, etc.
Special characters words like +, -, *, <, <=, etc
Figurative constants are constant values like ZERO, SPACES, etc. All the constant values of figurative constants are mentioned in the following table:
Data Name
Level Number
Picture Clause
Value Clause
Elementary items cannot be divided further. Level number, Data name, Picture clause and Value clause (optional) are used to describe an elementary item.
Group items consist of one or more elementary items. Level number, Data name, and Value clause (optional) are used to describe a group item. Group level number is always 01.
Data type can be numeric, alphabetic, or alphanumeric. Numeric type consists of only digits 0 to 9. Alphabetic type consists of letters A to Z and spaces. Alphanumeric type consists of digits, letters, and special characters.
Sign can be used with numeric data. It can be either + or .
Decimal point position can be used with numeric data. Assumed position is the position of decimal point and not included in the data.
Length defines the number of bytes used by the data item.
COBOL - Data Layout
COBOL layout is the description of use of each field and the values present in it. Following are the data description entries used in COBOL:
- Redefines Clause
- Renames Clause
- Usage Clause
- Copybooks
Redefines Clause
Redeifnes clause is used to define a storage with different data description. If one or more data items are not used simultaneously, then the same storage can be utilized for another data item. So the same storage can be referred with different data items.
Syntax
Following is the syntax for Redefines clause:
01 WS-OLD PIC X(10). 01 WS-NEW1 REDEFINES WS-OLD PIC 9(8). 01 WS-NEW2 REDEFINES WS-OLD PIC A(10).
Following are the details of the used parameters:
- WS-OLD is Redefined Item
- WS-NEW1 and WS-NEW2 are Redefining Item
Level numbers of redefined item and redefining item must be the same and it cannot be 66 or 88 level number. Do not use VALUE clause with a redefining item. In File Section, do not use a redefines clause with 01 level number. Redefines definition must be the next data description you want to redefine. A redefining item will always have the same value as a redefined item.
Example
IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-DESCRIPTION. 05 WS-DATE1 VALUE '20140831'. 10 WS-YEAR PIC X(4). 10 WS-MONTH PIC X(2). 10 WS-DATE PIC X(2). 05 WS-DATE2 REDEFINES WS-DATE1 PIC 9(8). PROCEDURE DIVISION. DISPLAY "WS-DATE1 : "WS-DATE1. DISPLAY "WS-DATE2 : "WS-DATE2. STOP RUN.
JCL to execute the above COBOL program.
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C //STEP1 EXEC PGM=HELLO
When you compile and execute the above program it produces the following result:
WS-DATE1 : 20140831 WS-DATE2 : 20140831
Renames Clause
Renames clause is used to give different names to existing data items. It is used to re-group the data names and give a new name to them. The new data names can rename across groups or elementary items. Level number 66 is reserved for renames.
Syntax
Following is the syntax for Renames clause:
01 WS-OLD. 10 WS-A PIC 9(12). 10 WS-B PIC X(20). 10 WS-C PIC A(25). 10 WS-D PIC X(12). 66 WS-NEW RENAMES WS-A THRU WS-C.
Renaming is possible at same level only. In the above example ,WS-A, WS-B, and WS-C are at the same level. Renames definition must be the next data description you want to rename. Do not use Renames with 01,77, or 66 level number. The data names used for renames must come in sequence. Data items with occur clause cannot be renamed.
Example
IDENTIFICATION DIVISION. PROGRAM-ID. HELLO. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-DESCRIPTION. 05 WS-NUM. 10 WS-NUM1 PIC 9(2) VALUE 20. 10 WS-NUM2 PIC 9(2) VALUE 56. 05 WS-CHAR. 10 WS-CHAR1 PIC X(2) VALUE 'AA'. 10 WS-CHAR2 PIC X(2) VALUE 'BB'. 66 WS-RENAME RENAMES WS-NUM2 THRU WS-CHAR2. PROCEDURE DIVISION. DISPLAY "WS-RENAME : " WS-RENAME. STOP RUN.
JCL to execute the above COBOL program.
//SAMPLE JOB(TESTJCL,XXXXXX),CLASS=A,MSGCLASS=C //STEP1 EXEC PGM=HELLO
When you compile and execute the above program, it produces the following result:
WS-RENAME : 56AABB
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