APF means "Authorized Program Facility". In a z/OS environment, APF is a facility that permits the identification of programs that are authorized to use restricted functions. APF-authorized programs must reside in one of the following authorized libraries:
SYS1.LINKLIB
SYS1.SVCLIB
SYS1.LPALIB
Authorized libraries specified by your installation
Authorized libraries are defined in an APF list. APF also prevents authorized programs (supervisor state, APF-authorized, PSW key 0-7, or PKM 0-7) from accessing a load module that is not in an APF-authorized library.
To find the datasets those are APF authorized:
Type TSO ISRDDN in your ISPF session (some shops need just ISRDDN with no TSO prefix) and press enter.
Type APF and press enter. It will bring up a list of all datasets that are APF authorized.
Remember that, if you like to use an APF authorized dataset in a job STEPLIB, make sure all the datasets in the STEPLIB are APF authorized.