Coupling facility data tables: storage statistics

These statistics are returned by the AXM page pool management routines for the pools AXMPGANY and AXMPGLOW. Storage in these pools is allocated in multiples of 4K pages on a 4K boundary. The most frequent use is for segments of LIFO stack storage.

Storage is initially allocated from the pool using a bit map. For faster allocation, free areas are not normally returned to the pool but are added to a vector of free chains depending on the size of the free area (1 to 32 pages). When storage is being acquired, this vector is checked before going to the pool bit map.

If there are no free areas of the right size and there is not enough storage left in the pool, free areas in the vector are put back into the pool, starting from the smallest end, until a large enough area has been created. This action appears as a compress attempt in the statistics. If there is still insufficient storage to satisfy the request, the request fails.

The statistics are described in detail in the DFHCFS9D data area.

Table 179. Coupling facility data tables: storage statistics
Statistic name Field Description
LOC=ANY storage pool statistics.
Name S9ANYNAM Name of the storage pool AXMPGANY.
Size S9ANYSIZ Size of the storage pool area.
S9ANYPTR Address of storage pool area.
S9ANYMX Total pages in the storage pool.
In Use S9ANYUS Number of used pages in the pool.
Free S9ANYFR Number of free pages in the pool.
Min Free S9ANYLO Lowest free pages (since reset).
Gets S9ANYRQG Storage GET requests.
Frees S9ANYRQF Storage FREE requests.
Fails S9ANYRQS GETs which failed to obtain storage.
Retries S9ANYRQC Compress (defragmentation) attempts.
LOC=BELOW storage pool statistics.
Name S9LOWNAM Pool name AXMPGLOW.
Size S9LOWSIZ Size of storage pool area.
S9LOWPTR Address of storage pool area.
S9LOWMX Total pages in the storage pool.
In Use S9LOWUS Number of used pages in the storage pool.
Free S9LOWFR Number of free pages in the storage pool.
Min Free S9LOWLO Lowest free pages (since reset).
Gets S9LOWRQG Storage GET requests.
Frees S9LOWRQF Storage FREE requests.
Fails S9LOWRQS GETs which failed to obtain storage.
S9LOWRQC Compress (defragmentation) attempts.

Related reference
Coupling Facility Data Table Pools Report
Interpreting server statistics
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