Tuning CA PMO › Addressing Special Tuning Concerns › Specifying an Appropriate Amount of Virtual Storage

Specifying an Appropriate Amount of Virtual Storage

If CA PMO runs out of virtual storage, you may receive the following message when it tries to manage a library:

PMO691I GETMAIN FAILED - VIRTUAL STORAGE EXHAUSTED. 
REASON=HT/DCB. DSN=data set name

This message appears if the GETMAIN fails for the hash table or for the DCB for this library. If the GETMAIN failure is due to a DCB, CA PMO tries to stop managing a library that has little or no directory search activity. If the problem is a GETMAIN failure for a hash table, CA PMO tries to stop a larger library with little or no directory search activity. If it cannot do that, it stops managing any two libraries that have little or no directory search activity.

When CA PMO uses up its storage during initialization, it issues a GETMAIN message for every library that was specified on the INCLPRVT parameter. CA PMO may also issue this message after initialization if you specify the F PMO,INCLPRVT command, or if CA PMO automatically tries to include a library.

If the virtual storage area is exhausted when CA PMO tries to automatically add a library, it looks for libraries with little search activity and stops managing them. This allows it to reclaim some storage. If the problem occurs for an automatically included library, the Virt Stg Exhausted field on the D6 display shows a minimum estimate of the directory searches that CA PMO could not handle because of GETMAIN failures. If the display shows that the virtual storage exhausted exceeds 1%, allocate a larger region size with the JCL REGION parameter. As a general rule, you allocate one megabyte for every 13,000 directory entries to be stored in hash tables. The virtual storage size of the CA PMO address space is controlled by the IEFUSI user exit. The default for this exit is 32 MB, which is enough storage for 416,000 directory entries.

You do not need to worry about allocating too much storage. CA PMO does not actually use the storage unless it is needed. The REGION parameter and IEFUSI exit control only virtual storage, not processor storage. As a result, if a library has no directory searches (or if only a small percentage of its members are ever accessed), its hash table pages remain in auxiliary storage and are not moved to processor storage.

Each offline report shows the amount of virtual storage used by the library.

Note: The amount of ECSA storage used for CA PMO SVC intercepts, the managed list, and library statistics does not contribute to the virtual storage controlled by the virtual storage area.