OPEN TCB excess TCB scan algorithm in CICS TS
Hello,
Looking at the EOD statistics, I see that there is a CICS Transaction Server for z/OS (CICS TS) internal process named "Excess TCB's SCAN", aimed to detach the unused OPEN Pool MVS TCB's and make them available for new requests. I would like to know how the scans frequency is determined, if the algorithm is based on the TCB limit values for L8, T8, ..., or what else, what are the thresholds beyond which the region can be in a potential trouble?
This information is important for tuning projects and to determine if additional target regions (AOR's) are needed in a workload balancing environment, because the process may cost unproductive processor consumptions in case the number of scans becomes too high.
Thanks a lot in advance
Hi @EmilioGuarnieri,
The Excess TCB's SCAN is performed by CICS system task SMSY. This normally runs every 5 minutes but in stress situations (like SOS) it will run every 2 seconds until the situation that caused the stress has been resolved.
Posted on behalf of Adrian Bull
IBM CICS TS Development