Analyzing CICS TCB Dispatcher Metrics – Part 2 (T8 TCBs)

Analysis of selected CICS Statistics and Transaction timing metrics relative to T8 TCBs which the CICS Dispatcher uses to dispatch Java programs which are zIIP eligible.

More CICS Statistics Videos

1. Assessing CICS Storage Health
2. Assessing CICS Transaction & Enqueue Health
3. CICS Transaction Class Metrics
4. CICS TCB Dispatcher Metrics – Part 1
5. CICS TCB Dispatcher Metrics – Part 2 (T8 TCBs)

Video Transcript

What you might have noticed here real quick is also that the number of T8 TCBs is much higher for this group of regions. And the documentation tells us that those are used by CICS for Java programs. So again, if we look at the peak TCBs that are in use and look at that set of regions by TCB mode, there are those T8 TCBs, and we can look at those across a broader time interval. And let’s go ahead and look at it kind of over a month interval, and when we do that for this type of TCB, we see lots of increases of the numbers at many different times across many different days, and not just at that one interval that we’ve been looking at. So, the CICS statistics data provides extensive metrics on how the dispatcher is managing each of the many types of TCBs within the regions and the CICS transaction data captures CPU time for each TCB type at the transaction level, which we’re going to see shortly. We can also view the groups of regions where zIIP eligible work is executing.

And you might remember that this matches the CICS group we saw earlier in the statistics data with many T8 TCBs in use. And I mentioned at that time that CICS uses T8 TCBs for Java programs, which are zIIP eligible. So let’s see if I was telling the truth, right? Let’s make note of the primary transactions here in that group that are using zIIP. And so DWRU,  DWR1, DWWU and then let’s explore how those transactions stack up on CPU consumed on the T8 TCB. So I’m going to go ahead and capture that in the dashboard.

All right, so let’s look at the CPU view by transaction, and we want to look at the actual CPU time. We want to focus particularly on that T8 TCB time. So let’s remove all the other types of TCB time. And when we do that, we see that sure enough, it’s those same three transactions that we saw earlier in that CICS group that are the ones that are consuming the T8 TCB. So that correlates with what we saw on the zIIP CPU time as well.