RACF® allows for UIDs and GIDs within the range of 0-2,147,483,647. However, the tar command and some interchange formats supported by the pax command might not be able to properly handle values above 2,097,151. Because they are used often, you should take these limitations into consideration when assigning UIDs and GIDs.

When restoring a UID or GID, if the pax or USTAR format was used during writing, pax and tar will first attempt to set the UID or GID during the restore using the user or group name stored in the archive. (Of course, the user must have the appropriate privileges to set the UID or GID). If this name is defined on the target system, then the UID or GID is set to whatever UID or GID is associated with the name defined on the target system. (The UID or GID is set, whether or not it matches the UID or GID in the archive, which means that this could be a problem if the name stored on the target system is coincidental rather than intentional).

If the user or group name is not defined on the target system, or if the archive is using the original tar format, then the UID or GID stored in the archive is used. If the UID or GID was originally greater than 2,097,151, and the archive was not created with the pax format, then the archive contains an incorrect version of the UID or GID value due to truncation. This situation will then result in that same incorrect UID or GID value being restored. However, if the archive was created with the pax format, then the original correct UID or GID is restored. The correct values are restored because the pax format supports UID or GID values up to 2147 483647.

In summary, large UIDs and GIDs might not be correctly restored by pax and tar. Using the pax format (the preferred method) can avoid this situation, because it supports values up to 2,147,483,647. (the maximum supported by RACF). Using the USTAR format might also avoid this situation, but only if the target system has the same user or group name defined and that name represents the same user or group as it did on the source system. Or, use UID or GID values within the limits for the archive format being used. See the description of pax and tar in z/OS UNIX System Services Command Reference for more information about these commands.