Potentially, any performance measurement tool, including statistics and the CICS® monitoring facility, may tell you something about your system that help in diagnosing problems. You should regard each performance tool as usable in some degree for each purpose: monitoring, single-transaction measurement, and problem determination.
Again, CICS statistics may reveal heavy use of some resource. For example, you may find a very large allocation of temporary storage in main storage, a very high number of storage control requests per task (perhaps 50 or 100), or high program use counts that may imply heavy use of program control LINK.
Both statistics and CICS monitoring may show exceptional conditions arising in the CICS run. Statistics can show waits on strings, waits for VSAM shared resources, waits for storage in GETMAIN requests, and so on. These also generate CICS monitoring facility exception class records.
While these conditions are also evident in CICS auxiliary trace, they may not appear so obviously, and the other information sources are useful in directing the investigation of the trace data.
In addition, you may gain useful data from the investigation of CICS outages. If there is a series of outages, common links between the outages should be investigated.