CHNGDUMP MAXSPACE

When you set up your IMS system for diagnostics, you should ensure that the space defined for the internal supervisor call (SVC) dump is adequate, and if not, use CHNGDUMP MAXSPACE to modify it.

Ensure that an adequate CHNGDUMP MAXSPACE value is specified to hold the internal supervisor call (SVC) dump.

  • Use the COMMNDxx member of the SYS1.PARMLIB data set to issue the appropriate CHNGDUMP command during IPL.
    • For example: CD SET,SDUMP,MAXSPACE=1000M
      • Default size is 500 MB
      • 2500 MB or larger is standard for large multi-address space SVC Dumps.
      • One way to estimate the amount of storage needed for the SVC dump is to calculate the total amount of global storage in use by adding the amount of storage used by all the regions (at peak usage) as viewed by online monitor programs.
      See z/OS® MVS Diagnosis: Tools and Service Aids, z/OS MVS Initialization and Tuning Reference, and z/OS MVS System Commands for complete details.
  • Advantages:
    • Higher likelihood that SVC dumps are captured in their entirety without worry of partial dump.
  • Considerations:
    • Ensure that local page data sets are large enough to contain their normal peak load, plus additional SVC dumps.