The following discussion shows ways to help you obtain better CPU utilization:
Use the Language Environment RPTSTG(ON) option to produce the storage report. Specify the reported storage amount in the corresponding Language Environment storage run-time options.
Put the commonly used Language Environment library routines in (E)LPA. The following lists the recommended candidates for PL/I:
See z/OS Language Environment Installation and Customization under OS/390 or z/OS Language Environment Customization for a complete list of library routines that can be put in (E)LPA.
Use AMODE(31) for your application, if possible, so you can specify Language Environment ALL31(ON) option. If ALL31(ON) is in effect, there will be no AMODE switching among library routines.
All PL/I condition handling is expensive and should only be used where appropriate. Overuse of PL/I condition handling will degrade the performance of your application.
On MVS, use BLKSIZE(0) for an output file that can be blocked. DF/SMS determines the optimal block size for you which can improve the file performance.
You can get a better CPU performance if you use LRR. When LRR is used, Language Environment keeps certain Language Environment resources in storage when an application ends. Subsequent invocations of programs that use LRR is much faster because the Language Environment resources left in storage are reused.
For example, you can use LRR for your IMS/DC environment to improve performance.
Note that because LRR leaves Language Environment resources in the storage for a long period of time, you must assess your storage availability to accommodate the situation.