IFC record count (BSTATDR)

LATCH CNT

Number of level 01 through 32 latch contentions (QVLSLC01 through QVLSLC32)

Tuning Tip: You can usually ignore these counters unless they exceed 1000 contentions per second. For latch counters 14, 19 and 24, try the performance tuning actions listed below to reduce contentions. The other latch counters can not be tuned externally. However, occasionally DB2 performance APARs reference high rates of contention for other latches.

• LC14: Buffer pool Least Recently Used (LRU) chain latch contention. If this contention rate is too high, move the highly accessed small objects to a different buffer pool. If you can take advantage of data space buffer pools (using an IBM zSeries processor and OS/390 2.10 or above), use data space buffers. If the buffer pool hit ratio is 100% or 0%, use FIFO (First In First Out) for the Page Steal Algorithm Parameter (PGSTEAL) instead of the default LRU algorithm in the ALTER BUFFER POOL command.
• LC19: Log manager latch contention. If this contention rate is too high, increase the Log OUTBUFF Zparm parameter. If this contention rate is too high in a non-data-sharing environment, consider data sharing configuration.
• LC24: Environmental Descriptor Manager (EDM) pool LRU chain latch contention. Use the bind options ACQUIRE (use) and RELEASE (deallocate) on the most frequently used plans and packages to reduce the contention. If this change affects too many plans and packages, you may need to increase the size of the EDM pool.