Recommended IDMS dump options and type of dump

Products

• IDMS
• IDMS - Database

Issue/Introduction

What system dump options in MVS does IDMS need to get the information necessary for debugging? Also what type of dump is preferred: SYSUDUMP, SYSMDUMP, etc?

Environment

IDMS - all supported Releases

Resolution

IDMS basically needs a full address space dump. Also if there are any dump diagnostic software installed it should be disabled in the IDMS region.

The preferred dump is an IPCS formatted dump which is acquired in the SYSMDUMP dataset or the SYS1.DUMPnn system dump datasets.

When an error or occurs that generates a system snap an SVC dump is written to a z/OS system dump dataset (SYS1.DUMPnn).

If the IDMS region abends and SYSIDMS parameter ABEND_SVC_DUMP=ON is specified (this is the default) an SVC dump will be taken to the system dump data sets (SYS1.DUMPxx) before the address space terminates.

A dump will also be taken depending on what xxxDUMP DD statement is present. 

MVS will first look for a SYSUDUMP DD (SYSUDUMP is formatted and readable like any output). If the SYSUDUMP DD is not found, MVS will then look for a SYSMDUMP DD. If found you will get the preferred IPCS formatted dump. If neither DD statements are found, then no dump will be produced. 

To get the dump IDMS requires you can display the dump options in MVS with the CONSOLE COMMAND "D D,O".

  SYSABEND- ADD PARMLIB OPTIONS SDATA=(NUC,SQA,LSQA,SWA,TRT,CB,ENQ,DM,
                       IO,ERR,PCDATA,SUM,ALLVNUC), PDATA=(SA,REGS,LPA,
                       JPA,PSW,SPLS,SUBTASKS)
 
  SYSUDUMP- ADD PARMLIB OPTIONS SDATA=(LSQA,TRT,CB,ENQ,DM,IO,ERR,
                       PCDATA,SUM), PDATA=(SA,REGS,LPA,JPA,PSW,SPLS,
                       SUBTASKS)
 
  SYSMDUMP- ADD PARMLIB OPTIONS (NUC,SQA,LSQA,SWA,TRT,RGN,LPA,CSA,SUM,
                       ALLNUC,GRSQ)
 
  SDUMP- ADD OPTIONS (ALLPSA,PSA,NUC,SQA,LSQA,RGN,LPA,TRT,CSA,SWA,
                       SUMDUMP,ALLNUC,GRSQ),TYPE=(XMEME),
                       BUFFERS=00000060K,MAXSPACE=00015000M,
                       MSGTIME=99999 MINUTES

The MVS dump options can be changed with the CD console command (CHNGDUMP). Examples can be found in SYS1.PARMLIB(IEACMDnn).

The IDMS startup JCL should ONLY have a SYSMDUMP DD (no other dump DD's). Make sure the SYSMDUMP DD dataset is big enough to hold the entire dump. Start with a very large allocation at first and then after a dump you can modify the size accordingly.

If system snaps are enabled and optional bit 176 is off in RHDCOPTF, then if a CV task abend requests a System Snap, an SVC dump to the SYS1.DUMPnn datasets will be written instead of writing the snap to the IDMS log as in previous releases. The SVC dump contains the storage of the whole IDMS region. Any IDMS error message with a severity of 2, 4 or 8 will generate an SVC dump. The most common one is DC027002 SYSTEM MODULE PROGRAM CHECKED.

Messages DC009001 and DC009002 give information and the title of the SVC dump requested by the IDMS CV.

Also note that the dumps taken to the SYSMDUMP & SYS1.DUMPnn datasets are IPCS formatted dumps and generate the least overhead in MVS when a job abends. It has less overhead because no formatting of the dump is done.

Additional Information

See documentation section Dump Options for Abnormal System Termination.