The RACF® subsystem must be able to use z/OS® UNIX socket APIs to communicate via TCP/IP in an RRSF network. To allow the subsystem to use these APIs, you must ensure that the user ID for the RACF subsystem is assigned a z/OS UNIX UID, and that its default group is assigned a GID. For information about assigning UIDs and GIDs, see z/OS Security Server RACF Security Administrator's Guide.