The local UTM cache memory is an area in virtual memory which is managed in 2KB, 4KB or 8KB units, depending on the generation. openUTM uses this cache as a global buffer area for access to the page pool, i.e. the processes of a UTM application handle all access to page pool data via this storage area. If the cache memory is sufficiently large, UTM allows you to optimize read/write access to the page pool. The main advantage of this is that read operations can be reduced if page pool data from a previous transaction (possibly written by another process) is still available in the cache memory.
The following values are defined during UTM generation:
the size of the cache memory
the percentage of cache memory pages to be written to the page pool if space is required for new data; this can be modified during operation by administration
whether the cache is to be located in the program address space or in one or more data spaces (only on BS2000 systems)
The administration functions allow you to find out whether the cache memory is being used in a currently running application.
| There is no universal formula for determining the ideal value for this parameter. You will have to base your decision on comparisons and performance measurements. However, you will find a few pointers and tips in the openUTM manual “Generating Applications”. |
