CICS Job Failures

The CICS region itself is a batch job (or started task). When that job fails, nothing runs - so diagnosing region startup failures quickly is a core production skill.

Region fails during initialization

• DFHSIP parameter errors - a misspelled SI override or bad START value stops initialization immediately. Read the DFHSI messages at the top of the job log.
• APPLID conflicts - the APPLID is already in use by another region or a hung address space. Choose a free APPLID or stop the other region.
• Missing DD statements - STEPLIB, DFHRPL, journals, catalogs and dump datasets must all be present and spelled correctly.
• Catalog or journal dataset problems - corrupted or full catalogs stop startup. Restore from backup or reformat with START=INITIAL.

A typical region startup JCL

• Example of the JCL that starts a CICS region:-
  //CICSPROD JOB (ACCT),'CICS REGION',CLASS=A,MSGCLASS=X
  //CICS EXEC PGM=DFHSIP,PARM='SI,START=AUTO,APPLID=CICSPROD'
  //STEPLIB DD DSN=CICSTS.SDFHLOAD,DISP=SHR
  //DFHRPL DD DSN=MYAPP.LOADLIB,DISP=SHR
  // DD DSN=CICSTS.SDFHLOAD,DISP=SHR
  //SYSUDUMP DD SYSOUT=*
  //DFHDMPA DD DSN=PROD.CICS.DFHDMPA,DISP=SHR
• STEPLIB points to the CICS load library; DFHRPL lists the application load libraries in search order.
• Always keep a known-good copy of the startup JCL - most startup failures are JCL changes gone wrong.

Reading the failure

• The job log and MSGUSR tell the story: DFHSI messages show how far initialization got before failing.
• An S0C4 or S0C1 in DFHSIP usually means a bad PARM or a missing module - check STEPLIB first.
• If the region starts then dies, look at the console log for the abend code and the last successful initialization step.