The IBM manual that states there are 3 ways to provide UID 0 access. They are as follows:
Release : 15.0
Component : CA LDAP Server
Top Secret can use UNIXPRIV(SUPERUSER.FILESYS) or (BPX.SUPERUSER) rule.
IBMFAC(BPX.SUPERUSER) is the same as giving UID(0), however since UID(0) has been removed and the ACID now has a unique UID, and you can pin point them for accountability
With UID(0) you can't tell which of the ID's that have that access did something.
Superuser Granularity for UNIXPRIV documented here.