Caching UIDs and GIDs improves performance for commands such as ls -l, which must convert UID numbers to user IDs and GID numbers to RACF® group names. RACF allows you to cache UID and GID information in virtual lookaside facility (VLF).

Guideline: To avoid performance degradation, VLF should be made active. For more information about performance considerations, see RACF performance considerations.