Assigning identifiers for groups

All groups should be assigned unique GIDs. If you assign groups the same GIDs, you should warn users of the following effects:

The groups share ownership and access to the same files.
Security audit records show the GID, but do not show the RACF® group if it was in the supplemental group list; see Activating supplemental groups.
Services such as the getgrgid() callable service cannot distinguish which group is meant. The services return data about one of the groups, but which group is unpredictable.

To assign a non-unique GID, you can use the SHARED keyword of the RACF ADDGROUP or ALTGROUP command if the SHARED.IDS profile is defined in the UNIXPRIV class.