Collecting data about a control region wait or hang

When an IMS control region waits or hangs, IMS can appear frozen or lose partial function. The most critical piece of information in diagnosing such problems is the z/OS® SVC dump.

Recommendation:  Do not use the z/OS MODIFY dump (F jobname,DUMP) command as a source of IMS diagnostic information. This command adds unnecessary complexity to the dump while processing the modify abends.
Obtain a z/OS SVC dump by issuing this series of commands: 
DUMP COMM=(dump title) R id JOBNAME=(j1,j2,j3,j4,j5,j6),
     SDATA=(CSA,PSA,RGN,SQA,SUM,TRT),END
In the previous example,
j1
is the IMS CTL or DBCTL region job name
j2
is the IMS DL/I region job name
j3
is the suspicious IMS dependent region job name, if any
j4
is the suspicious CCTL (CICS®) region name, if any
j5
is the IRLM region job name (if IRLM DB locking is used)
j6
is the DBRC region job name

Also, consider dumping related regions:

  • IMS Control region
  • IMS DLI/SAS region
  • DBRC region
  • IRLM region
  • CQS
  • Operations Manager
  • Resource Manager
  • Structured Call Interface
  • Troublesome IMS dependent regions
  • CCTL regions
  • ODBA
  • IXGLOGRC
  • z/OS Resource Recovery Services
  • APPC
  • VTAM®
  • WLM
  • TCPIP
  • WebSphere® Application Server
  • ESAF - Db2 for z/OS, IBM® MQ, others
  • Other Regions
  • Other IMSplex members with all their related regions

Most likely, a dump of the IMS CTL, DL/I, and a suspicious dependent region or CCTL region is sufficient to solve wait or hang problems. Occasionally, the DBRC and IRLM (if used for DB locking) regions are a factor, so include DBRC and IRLM.

If IMS is not completely stopped (for example, IMS commands can still be entered, BMPs are still processing, and some transactions still process), taking a second z/OS SVC dump will help differentiate normal IMS processing from the problem.