Tuning stack storage

For best performance, the initial stack segment should be large enough to satisfy all requests for stack storage. The Language Environment storage report generated by the RPTSTG(ON) option (see z/OS Language Environment Programming Reference) shows you how much stack storage is being used, the total number of segments allocated to the stack, and the recommended values for the STACK runtime option. An initial stack segment that is too large can waste storage and degrade overall system performance, especially under CICS® where storage is limited.

You can tune stack storage by using the Language Environment STACK and THREADSTACK runtime options; consult z/OS Language Environment Programming Reference for details.

RPTSTG(ON) and the STORAGE runtime option (see z/OS Language Environment Programming Reference) can have a negative affect on the performance of your application, because as the application runs, statistics are kept on storage requests. Therefore, always use the IBM-supplied default setting RPTSTG(OFF) when running production jobs. Use RPTSTG(ON) and STORAGE only when debugging or tuning applications.