Reduce CPU time and improve performance
Article ID: 69163
Updated On:
Products
Issue/Introduction
When there are no ASRs for a particular Environment to process, the launch sysparm can logically disable the environment launches. This results in reduced CPU time and improved run time performance.
Resolution
The following sysparms control the launch of the Environments that are used during z/OS data set operations:
* SPECIFY N FOR ANY ENVIRONMENTS NOT USED - TO IMPROVE PERFORMANCE *
PLSACS (Y) * LAUNCH ACS ENVIRONMENT
PLSLALLO (Y) * LAUNCH ALLOC ENVIRONMENT
PLSLDEF (Y) * LAUNCH DEFINE ENVIRONMENT
PLSLEOV (Y) * LAUNCH EOV ENVIRONMENT
PLSLEOVV (Y) * LAUNCH EOVVSAM ENVIRONMENT
PLSLEXT (Y) * LAUNCH EXTEND ENVIRONMENT
PLSLOLD (Y) * LAUNCH OLD ENVIRONMENT
PLSLPREA (Y) * LAUNCH PREALLOC ENVIRONMENT
PLSLREL (Y) * LAUNCH RELEASE ENVIRONMENT
PLSLRENM (Y) * LAUNCH RENAME ENVIRONMENT
PLSLSCR (Y) * LAUNCH SCRATCH ENVIRONMENT
PLSLSPA (Y) * LAUNCH SPACE ENVIRONMENT
The default value of each of the launch sysparms is (Y), which causes each Environment to launch for applicable allocation requests. If you have no ASRs that do any processing in an environment, then you logically disable that environment from launching by specifying a value of (N) in your sysparm override member. This command will refresh all Vkgparms:
F vam,PARMREF
Additional Information
A major financial institution had been doing testing for a possible fix to improve performance. L2 asked the user to test the settings of one of these Vkgparms.
The result of the test was:
PLSLPREA (N) - 20% decrease in Catalog CPU usage and a 25% reduction in Catalog I/O, vs. when this VKGPARM was set to (Y).
Also refer to the KB article Performance of Allocate for information on other VKGPARMS that will improve Allocate performance.
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