Processor utilization

CPU fields are used to measure the amount of work performed by the processor, as opposed to work performed by the I/O and storage subsystems. CPU time consists of the sum of the following five components.

Task Control Block (TCB)

The CPU time used to perform user program activity on behalf of user tasks for a job step.

Service Request Block (SRB)

The CPU time used to perform system service requests on behalf of user tasks for a job step.

Hiperspace™ Processing Time (HPT)

If the user task reads from or writes to a Hiperspace using the HSPSERV macro, this is the amount of CPU time used to service these reads and writes.

I/O Interrupt Processing (IIP)

The CPU time used to handle input/output (I/O) interrupts on behalf of user tasks for a job step.

Region Control Task (RCT)

If the user task is swapped out while running, this is the amount of CPU time used to swap the task out and back in again.