With the su command, you can switch to any user ID, including the superuser. A user can switch to superuser authority (with an effective UID of 0), if the user is permitted to the BPX.SUPERUSER resource in the FACILITY class within the Resource Access Control Facility (RACF®). Either the ISPF shell or the su shell command can be used for switching to superuser authority.

If you do not specify a user ID, the su command changes your authorization to that of the superuser. If you specify a user ID, su changes your authorization to that of the specified user ID.

When you switch to superuser (UID 0) without specifying a user ID, you keep your MVS™ identity (TSO/E ID). You keep your access authority to MVS data sets, while gaining authority to access any files.

When you change user ID by specifying a user ID and password or password phrase, you assume the MVS identity of the new user ID even if the user ID has UID 0.

If you use the –s option on the su command you will not be prompted for a password. Use this option if you have access to the BPX.SRV.userid SURROGAT class profile. The userid is the MVS user ID associated with the target UID.

exit

For more information, see the su command description in z/OS UNIX System Services Command Reference.