The hit rate for accessing the catalog cache, where the parsed SQL statements are administered, is too low. For a balanced database application the catalog cache hit rate should be around 90%. If programs or subprograms are started, the hit rate may temporarily drop to very low rates. However, the 15-minute average should not be below 85%.

The catalog cache should be about 100 pages per database session. This can be checked using XPARAM and the parameters MAXUSERTASKS and CAT_CACHE_SUPPLY. The catalog cache is dynamically increased during the active database sessions, and released by a RELEASE statement. The current cache sizes can be determined using SELECT * FROM CONNECTEDUSERS. If sessions are using considerably more than 100 pages, the catalog cache should be increased for the medium-term, as long as the server’s memory can support this.