TOTAL STORAGE NOTIFIES reported to OMEGAMON XE for CICS is growing, at an alarming rate

CICS TS uses STORAGE NOTIFIES to report the condition of:

• tasks suspended waiting for storage, or

• a potential constraint.

CICS will issue a trace entry, AP F110 APSM ENTRY - FUNCTION(STORAGE_NOTIFY), which details the available storage in the DSAs. In this case, one of the trace point values indicates "DSAS_CONSTRAINED(YES)", and corresponds to the information propagating to OMEGAMON, where the TOTAL is incremented. The provided trace shows these STORAGE_NOTIFY entries are issued about every 10 seconds.

In many cases, a constraint condition is set only if there are less than 5 extents free in the subject DSA.
But when any DSA is specified as a fixed size in the CICS System Initialization Table (SIT), CICS will always treat the DSAs as constrained so that the loader can adjusts its targets in that DSA. This is true even if there is free storage elsewhere.

This means that storage notifies are driven more frequently when you have a fixed DSA specified, even for relatively small changes to available DSA storage. This is as designed in the storage notify code.

You might want to consider NOT setting a fixed size for each of the DSA size SIT parameters (for example CDSASZE, RDSASZE, UDSASZE, SDSASZE, ECDSASZE, ERDSASZE, EUDSASZE, and ESDSASZE), and instead letting CICS manage this for you. If you look at the description of any of these parameters, for example SDSASZE), it says the default size is 0, indicating that the DSA size can change dynamically. A non-zero value indicates that the DSA size is fixed.

See Fixing short-on-storage conditions caused by subpool storage fragmentation for more information on why you might want to enable the CICS self-tuning mechanism for storage.