Analyzing CICS TCB Dispatcher Metrics – Part 1

CICS Statistics data provides many metrics that provide insights into how the CICS Dispatcher is utilizing the many types of TCBs it uses to manage the execution of multiple units of work within regions.

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

The statistics data also captures many metrics on all the distinct TCBs that CICS manages to carry out all the work that’s going on within the regions that are managed by the CICS Dispatcher. So let’s go ahead and select that group we’ve been looking at. And now let’s look at the maximum TCB utilizations for each of the types of TCBs in the group. So typically we’ll be very interested in the single QR TCB, because it can be a point of constraint and that’s one that’s often assessed against some threshold as a health metric. So for this group of regions, the QR TCB utilizations never even reached 4%. So there’s clearly no concern there. Let’s go ahead and grab that one in the dashboard. So in contrast, this CICS dynamically attaches additional TCBs of many other types as it needs, including the workhorse L8 TCBs, and so we can look at those utilizations across the regions and we can see they tend to be very comparable across a couple of different types of sets of regions here.

All right. So the dispatcher statistics also capture metrics on the number of TCBs attached and used. So again, let’s go ahead and look at that same set of regions by the type of TCB. And we can see that during this time interval that the number of TCBs that were in use spiked up very significantly. So let’s go ahead and save that in our dashboard. And again, if we look at it across regions, we can see that it happened across many of the regions in that group. So seeing that sizeable number of L8 TCBs leads us maybe to wonder about the numbers of all types of TCBs that compared across all the other types of groups of regions in this environment.

So we can see, for example, that for L8 TCBs or some other groups that have comparable numbers but we’ve got this one group that’s far higher in terms of the number of L8 TC BS that it had in use. So let’s go ahead and add this to our dashboard.

All right. And then if we want, we can look at that across the regions and we can see that there are several regions in the group that exceeded 100 TCBs, and if we want to look at that over time, we can see that those numbers all spiked in that same eight and nine o’clock interval that we’ve been looking at.

So, so far on this learning journey of CICS Statistics data, we’ve seen other metrics as well that reflected a typical behavior in those morning hours of 8/31. We saw that was short on storage, we saw it with MAXTASKS and here we saw it in terms of CICS creating lots of TCBs. So that leads me to wonder if that might be the case, you know, for these spikes of TCBs for that group. So again, we could view that across the interval, and if we did that, we would see again that that was an unusually high spike that occurred on 8/31.