Region size considerations

Set the REGION parameter on the EXEC card in the JCL according to the virtual storage requirements for thread and Java™ heap settings in the Gateway daemon.

For more information about calculating the required setting see Tuning the gateway to avoid out of memory conditions.

To verify the actual region size allocated for the CICS Transaction Gateway, include the CTGDBG DUMMY DD statement in the JCL step for CTGBATCH. Message CTG0813I shows the current region size.

The following parameters can also limit the values that you can choose for the REGION parameter:
  1. The ASSIZEMAX parameter of the OMVS segment of a RACF® user ID; for more information see the RACF Command Language Reference.
  2. The UNIX System Services MAXASSIZE parameter found in SYS1.PARMLIB(BPXPRMxx); for more information see the UNIX System Services Planning. The value specified for ASSIZEMAX overrides any value provided by the MAXASSIZE parameter
Note: Use of REGION=0M. The actual region size available when REGION=0M is used is unpredictable, due to optional implementation of the system exit routine IEFUSI. REGION=0M indicates that the address space must be given as much memory as possible. However, large REGION sizes might be policed by the IEFUSI exit, and reduced to a default size. If this default size is too small the CICS Transaction Gateway is likely to fail with out of memory problems.

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Timestamp icon Last updated: Tuesday, 19 November 2013


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