Question & Answer
Question
How do I calculate the amount of CPU time that CICS Transaction Server for z/OS (CICS TS) spent on a IBM z Systems Integrated Information Processor (zIIP) processor?
Answer
Topic Performance data in group DFHTASK in the CICS TS documentation describes the following calculation under 436 (TYPE-S, 'CPUTONCP', 12 BYTES):
...To calculate the task processor time that was spent on a specialty processor (zIIP or zAAP), subtract the time recorded in the CPUTONCP field from the time recorded in the USRCPUT field.
The topic also describes the DFHTASK fields (CPUTONCP and USRCPUT) that are used in the calculation:
008 (TYPE-S, 'USRCPUT', 12 BYTES)
Processor time for which the user task was dispatched on each CICS TCB under which the task ran. The TCB modes managed by the CICS dispatcher are: QR, RO, CO, FO, SZ, RP, SL, SP, SO, EP, L8, L9, S8, TP, T8, X8, X9, and D2. Be aware that, for each CICS release, new TCB modes might be added to this list, or obsolete TCB modes might be removed.
436 (TYPE-S, 'CPUTONCP', 12 BYTES)
The total task processor time on a standard processor for which the user task was dispatched on each CICS TCB under which the task ran.This field is a component of the task CPU time field, USRCPUT (field ID 008 in group DFHTASK).
The total task processor time on a standard processor for which the user task was dispatched on each CICS TCB under which the task ran.This field is a component of the task CPU time field, USRCPUT (field ID 008 in group DFHTASK).
How this data is reported in SMF30 versus SMF110
SMF30 collects data at address space level in 5 minute intervals. SMF110 collects data at the transaction level.
The Java™ Virtual Machine (JVM) in CICS has many threads that are unknown to CICS. Even the threads that are T8 TCBs can be used for internal Liberty work outside of a user task. Those threads accumulate zIIP CPU time that is not associated with or reported in any CICS task-related field, thus accounting for the differences between SMF30 and SMF110.
If there is a concern about the low zIIP time for user tasks, then it is necessary to look at the potential for the task to lose eligibility. A CICS dump with an internal trace that covers several user tasks can help identify any potential problems relating to CICS configuration.
It is also worth looking at the amount of time spent on a general CP while zIIP eligible. Just because a TCB is eligible to run on a zIIP doesn't mean that it will. If the zIIPs are currently in use, the task will run on a general CP.
If there is a concern about the low zIIP time for user tasks, then it is necessary to look at the potential for the task to lose eligibility. A CICS dump with an internal trace that covers several user tasks can help identify any potential problems relating to CICS configuration.
It is also worth looking at the amount of time spent on a general CP while zIIP eligible. Just because a TCB is eligible to run on a zIIP doesn't mean that it will. If the zIIPs are currently in use, the task will run on a general CP.
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Product Synonym
CICS/TS CICS TS CICS Transaction Server
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Document Information
Modified date:
04 February 2020
UID
ibm11168132