A summary of performance bottlenecks, symptoms, and causes

Table 14 contains a summary of potential performance bottlenecks, the symptoms you get if they are restricting the performance of your system, and the specific causes of the delays at each point.

Table 14. A summary of performance bottlenecks, symptoms and causes
Bottleneck Symptoms Possible causes
Initial attach to transaction manager CEMT INQ TASK does not know task.

Tracing shows long wait for attach to transaction manager.

  • Interval on EXEC CICS® START too long
  • Terminal not available
  • Remote system not available
Initial attach to dispatcher CEMT INQ TASK shows wait on MXT or transaction class.

Tracing shows long wait for attach to dispatcher.

MXT or transaction class limits set too low
First dispatch Performance class monitoring shows long wait for first dispatch.

Storage statistics show CICS has gone SOS.

  • MXT or transaction class limits set too low
  • Priority of task set too low
  • Insufficient storage
  • System under stress, or near it
SUSPEND / RESUME cycle Tasks take a long time to complete.
  • System loading high
  • Task time-out interval too large
  • CICS data sets are on volumes susceptible to MVS™ RESERVE locking

Related concepts
Finding the bottleneck
Why tasks fail to get attached to the transaction manager
Why tasks fail to get attached to the dispatcher
Why tasks fail to get an initial dispatch
A summary of performance bottlenecks, symptoms, and causes
Related tasks
Identifying storage stress
Interpreting storage manager statistics
Related references
Storage manager statistics
CHANGE TASK
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