Tuning Performance › Performance Considerations When Writing NCL › Commands to Control Resource Consumption by NCL

Commands to Control Resource Consumption by NCL

There are several commands that can be used to alter the performance of your region. These system performance commands include SYSPGT, SYSRCT, SHOW SYSWAIT, SHOW SYSPGT, and SHOW SYSRCT. These commands display and control resource consumption by NCL processes.

All NCL statements are assigned a processing unit weighting. SYSRCT and SYSPGT commands let you set up performance groups whereby an NCL process is placed into a forced wait if it consumes a certain amount of these processing units. This allows System Services to run with a high priority in the operating system, but prevents them from using all available CPU time if an NCL procedure starts looping.

System-level procedures should have a high priority. Short-term performance controls can be used to stop a runaway system procedure without impacting it in the long term.

The SHOW NCL command can also be used to indicate the performance group, priority, and current processing unit consumption. For more information about the SHOW NCL command, see the online help.

Important! Busy system procedures that do not wait because there is always a message available for &xxxREAD may be unfairly penalized by the short-term performance control. These should be reset using the following command:

SYSRCT G=4 P=0 SDELAY=(0,0,0,0)