(ZOS) SVC dumps

A SVC dump is a core dump initiated by the operating system generally when a programming exception occurs. SVC dump processing stores data in dump data sets that you pre-allocate, or the system allocates automatically as needed.

Alternatively, we can initiate an SVC dump through the MVS™ console, to gather diagnostic data for a 'hang' condition, for example. SVC dumps that you initiate this way are called console dumps.

One example of an abend that could occur is the EC3 abend. WebSphere Application Server for z/OS requests an SVC dump when a controller terminates a servant (region) with an EC3 abend when timeout conditions occur.

• Your installation can set parmlib options that determine what to dump, eliminate duplicate dumps, and so on. WAS for z/OS provides a dump parmlib sample in

   SBBOJCL(BBODMCCB)
  

  .
• The standard SDATA expected in a SVC dump:

   SDATA=(ALLNUC,CSA,GRSQ,LPA,LSQA,PSA,RGN,SQA,SUM,SWA,TRT),end
  

• If we cannot find an SVC dump for a specific abend, the installation might be using Dump analysis and elimination (DAE) to suppress the dump. If this is the case, we can change DAE to let the dump be taken or set a SLIP on the specific abend for a particular job name if the timeout is consistently happening. For further information, see:
  • z/OS MVS Diagnosis: Tools and Service Aids, GA22-7589 for details about using DAE.
  • z/OS MVS System Commands, SA22-7627 for details about the SLIP command, which controls SLIP (serviceability level indication processing), a diagnostic aid that intercepts or traps certain system events and specifies what action to take. Using the SLIP command, we can set, modify, and delete SLIP traps.

• When we initiate a console dump:
  • When we want an SVC dump of a servant region, also request a dump of the servant's controller region.
  • Unless you suspect a particular servant region as the source of a problem, dump the controller region and all of its servant regions.

• If syslog contains a message indicating that the maxspace limit was reached for this dump, the SVC dump might be a partial one that might not contain the data we need to diagnose the timeout. This limit means that the data set used for SVC dump is not large enough, and we have to change the size to capture a complete dump.

  If we are running WAS for z/OS with 64-bit support, and we specify RGN (region) in the SDATA parameter set, we will need to allocate a much larger space limit for the SVC dump.

• To view CEEDUMP contents within the SVC dump, use the IPCS verbexit LEDATA, with the CEEDUMP or NTHREADS options, to format and analyze Language Environment control blocks. For additional information, see z/OS Language Environment Debugging Guide, GA22-756 for instructions for using IPCS to format and analyze CEEDUMP contents.

See z/OS MVS Diagnosis: Tools and Service Aids, GA22-7589 for additional information about SVC dumps.

Diagnose problems (using diagnosis tools)

CEEDUMPs in the job log