Requirements for NFS

Table 1 summarizes the installation-wide exit routines that are provided by the NFS.

Table 1. List of installation-wide exits
Source Module Name	Load Module Name	Parameter List Mapping Macro	Description
GFSAUXL	GFSAUXL	GFSAULOG GFSAUDSA	Login security exit
GFSAUXF	GFSAUXF	GFSAUSEC GFSAUDSA	File security exit

GFSAUDSA is a sample skeleton for a user storage block.

The installation-wide exit routines are shipped with the NFS and they contain the dummy skeleton code. The source modules reside in the prefix.NFSSAMP data set and the macros reside in prefix.NFSMAC data set. (The value of prefix depends on the installation.) Before modifying or replacing these exits, you should review the functions and processing of these exit routines carefully. These are basic requirements for all the NFS exit routines:

Exit routines must reside in an authorized program library and be accessible by the z/OS LOAD macro. NFS and installation-wide exit routines receive control in problem state key 8. Installation-wide exits are run as an APF-authorized task, because the Network File System is APF-authorized. As with any APF-authorized program, your exits should not be link-edited with APF-authorization. Only the main task, NFS, should have that link edit attribute.
Exit routines must be link-edited with AMODE(31).
The installation-wide exit routines are entered in AMODE(31) and can reside above or below the 16M line depending on the requirements of the installation-wide exits themselves.
Exit routines must be reentrant.
Exit routines must follow the standard z/OS register save and restore convention. The standard z/OS registers convention is:
- Register 1 contains the address of the exit parameter list.
- Register 13 contains the address of the caller's save area.
- Register 14 contains the caller's return address.
- Register 15 contains the address of the entry point for this exit routine. The server does not use return codes stored in register 15, but includes a parameter in the parameter list for exits that supply return codes.

Note:

Address parameters have null value (0) if the related data does not exist.
The length of each field can be found in the macros shipped. Field length can be changed in the future.