zFS runs as a z/OS® UNIX colony address space. There must be an entry in a BPXPRMxx parmlib member for ZFS and the ZFS PROC must be available. zFS is started by z/OS UNIX, based on the FILESYSTYPE statement for ZFS in the BPXPRMxx parmlib member. zFS can be started at IPL if the BPXPRMxx parmlib member is in the IEASYSxx parmlib member's OMVS=(xx,yy) list. It can also be started later by using the SETOMVS RESET=(xx) operator command.