CICS - COBOL Basics


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CICS programs are written in COBOL language in Mainframes. We will be discussing about writing a simple COBOL-CICS program, compiling it, and then executing it.

CICS Program

We will be writing a simple COBOL-CICS program which displays some message on the CICS output screen. This program is to demonstrate the steps involved in executing a COBOL-CICS program. Following are the steps to code a simple program −

Step 1

Login to Mainframes and open a TSO Session.

Step 2

Create a new PDS in which we will be coding our program.

Step 3

Create a new member inside the PDS and code the following program −

IDENTIFICATION DIVISION.
PROGRAM-ID. HELLO.
DATA DIVISION.
FILE SECTION.
WORKING-STORAGE SECTION.
01 WS-MESSAGE PIC X(40).
01 WS-LENGTH  PIC S9(4) COMP.
PROCEDURE DIVISION.
A000-MAIN-PARA.
   MOVE 'Hello World' TO WS-MESSAGE
   MOVE '+12' TO WS-LENGTH
   EXEC CICS SEND TEXT 
      FROM (WS-MESSAGE)
      LENGHT(WS-LENGTH)  
   END-EXEC
   EXEC CICS RETURN
   END-EXEC.	 

Step 4

After coding the program, we need to compile it. We can compile the program using the following JCL −

//SAMPLE JOB(TESTJCL,XXXXXX),CLASS = A,MSGCLASS = C  
//CICSCOB  EXEC CICSCOB,                                                
//COPYLIB = ABC.XYZ.COPYLIB,                            
//LOADLIB = ABC.XYZ.LOADLIB 
//LIB        JCLLIB ORDER = CICSXXX.CICS.XXXPROC                
//CPLSTP     EXEC DFHEITVL                                
//TRN.SYSIN  DD DSN = ABC.XYZ.PDS(HELLO),DISP = SHR     
//LKED.SYSIN DD *                                        
   NAME HELLO(R)                                          
//

Step 5

Open a CICS session.

Step 6

We will now install the program using the following command −

CEMT SET PROG(HELLO) NEW.

Step 7

Execute the program using the associated transaction-id. Transaction-id is provided by the Administrator. It will show the following output −

CICS Output

Program Compilation

The following flowchart shows the steps used in compiling a COBOL-CICS program −

CICS Compilation

Translator

The function of a translator is to check for syntax errors in CICS commands. It translates them into equivalent COBOL statements.

Compiler

The function of a compiler is to expand the COBOL copy books. It compiles the code after checking the source code for syntax errors.

Linkage Editor

The function of a Linkage Editor is to link different object modules to create a single load module.



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