Environment

Review Function Routines/Function Codes, which describes both the general environment on entry to your function routine and other programming considerations that your function routine should take into account.

If you decide to set up your subsystem to handle SMF SUBPARM option change calls, make sure that your function routine is in place before you enable the subsystem to handle SSI function code 58. IBM® recommends that you use the IEFSSVT macro to notify MVS™ that your subsystem should be given control whenever SMF SUBPARM Option Change calls are made. IEFSSVT macro services are available only to dynamic subsystems. Subsystems that are not dynamic can still use the IEFJSVEC service; see Building the SSVT and Enabling Your Subsystem for New Functions for more information.

Data areas commonly used by SSI function code 58 are mapped by the following mapping macros. IBM recommends you include them in your function routine:

IEFSSOBH
IEFJSSIB
IEFSSSM

The function routine receives control in the following environment:

Environment variable	Value
Minimum authorization	Supervisor state with PSW Key 0
Dispatchable unit mode	Task
AMODE	24-bit or 31-bit
Cross memory mode	PASN=HASN=SASN
ASC mode	Primary
Interrupt status	Enabled for I/O and external interrupts
Locks	No locks held
Control parameters	The SSOB, SSIB, and SSSM control blocks reside in storage below 16 megabytes.
Recovery	None

Figure 1 shows the environment at the time of the call for SSI function code 58.

Figure 1. Environment at Time of Call for SSI Function Code 58