Run COBOL + DB2 Batch with DSN and IKJEFT01

Why batch COBOL uses DSN RUN

Most Db2 batch applications run under the TSO Terminal Monitor Program in background mode. IKJEFT01 reads SYSTSIN commands, starts a DSN session for a subsystem, and the RUN subcommand loads your COBOL program in that Db2-connected environment. The plan named on RUN is the allocation unit that locates packages for the SQL your program issues.

Directly executing the COBOL module without DSN can work only in attachment models designed for that path. For classic TSO/batch Db2 COBOL, DSN RUN is the standard and safest teaching pattern.

Prerequisites

Also confirm commit strategy, restart checkpoints, and whether the job should stop on the first negative SQLCODE. A batch program that ignores SQLCODE can update partial data and still look “successful” in SDSF if it sets return code zero.

RUN command options

Steps: run the batch program

1. Assemble the JCL skeleton

Start with IKJEFT01, include Db2 libraries, allocate SYSTSPRT and SYSTSIN, and add every DD your COBOL program expects. Use DYNAMNBR when your shop standard includes it for DSN workloads.

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//EMPBATCH JOB (ACCT),'EMPRPT',CLASS=A,MSGCLASS=X,NOTIFY=&SYSUID
//*---------------------------------------------------------------*
//* Run COBOL Db2 batch program EMPRPT01 under plan TRAINPLN
//*---------------------------------------------------------------*
//GO       EXEC PGM=IKJEFT01,DYNAMNBR=20,REGION=0M
//STEPLIB  DD DISP=SHR,DSN=DSN.V12R1M0.SDSNEXIT
//         DD DISP=SHR,DSN=DSN.V12R1M0.SDSNLOAD
//         DD DISP=SHR,DSN=APP.TRAIN.LOADLIB
//SYSTSPRT DD SYSOUT=*
//SYSOUT   DD SYSOUT=*
//SYSPRINT DD SYSOUT=*
//EMPIN    DD DISP=SHR,DSN=APP.TRAIN.EMPIN
//EMPOUT   DD SYSOUT=*
//SYSTSIN  DD *
  DSN SYSTEM(DB2T)
  RUN PROGRAM(EMPRPT01) -
      PLAN(TRAINPLN) -
      LIB('APP.TRAIN.LOADLIB') -
      PARMS('/DEPT=A10')
  END
/*

2. Match PLAN and PROGRAM to the bind

PROGRAM must be the load module name. PLAN must be the plan that lists the collection containing package EMPRPT01. If your site uses multiple environments, double-check that the job is not pointing a production load module at a test plan, or the reverse.

3. Pass PARMS deliberately

The example uses a slash before application parameters, which is a common way to separate Language Environment runtime options from program arguments. If your program expects a different layout, follow its runbook. Never copy PARMS from an unrelated sample without reading the COBOL linkage section.

4. Keep the DSN step focused

IBM guidance is to keep DSN job steps short. If the application abends or returns a non-zero code, DSN typically terminates. Put unrelated utility work in separate steps so a Db2 application failure does not obscure later processing.

Verify results

• Confirm IKJEFT01 and application return codes in the job log.
• Read SYSTSPRT for DSN messages and RUN completion text.
• Inspect application SYSOUT for SQLCODE handling, record counts, and business totals.
• For updates, query a known key before and after, or reconcile input count to rows changed.
• On failure, capture PLAN, PROGRAM, LIB, subsystem, and the first negative SQLCODE before changing multiple things at once.

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-- Example post-run reconciliation for a reporting extract key
SELECT COUNT(*) AS EMP_COUNT
  FROM TRAINING.EMPLOYEE
 WHERE DEPT_CODE = 'A10'
   AND ACTIVE_FLAG = 'Y';

Common errors

Missing application DD names often surface as language-environment or COBOL file status problems before any SQL runs. When SQL never starts, check file allocations first. When SQL starts and fails immediately, check plan, package, and authorization next.

Explain It Like I'm Five

Think of IKJEFT01 as a helper who walks your COBOL robot to the Db2 school office. DSN SYSTEM opens the right school building. RUN PROGRAM tells which robot to start. PLAN is the hall pass that lists which binders of answers the robot may use. If the hall pass is wrong, the robot can stand up and still be told it may not open the binder.

Exercises

1. Write a DSN RUN command for program ORDUPD01, plan ORDPLAN, and library APP.PROD.LOADLIB.
2. List five DD statements a payroll extract program might need in addition to SYSTSIN.
3. Explain why a job can show IKJEFT01 RC=0 while business totals are wrong.
4. Create a failure checklist for SQLCODE -805 versus -818 in batch.
5. Describe how you would prove the batch job used the intended Db2 subsystem in a data sharing group.