IEFU83 — SMF Record Exit

Topics for This Exit Appear as Follows:

Defining the Exit in SMFPRMxx
Controlling the Exit Routine Through the Dynamic Exits Facility
Exit Routine Environment
Exit Recovery
Exit Routine Processing
Programming Considerations
- Macro Instructions and Restrictions
Entry Specifications
- Registers at Entry
Return Specifications
- Registers at Exit

The SMF record exit IEFU83 receives control when the caller invokes either:

The SMFWTM macro.
The SMFEWTM macro and specifies BRANCH=NO.

After exit routine processing, IEFU83 returns a code that specifies whether SMF is to write the SMF record to the SMF data set. IEFU83 does not receive control for records whose writing has been suppressed either because of a system failure or because of options selected at IPL time or via the SET SMF command.

You can use IEFU83 to:

Select or suppress those records to be written to the SMF data set. For example, an installation with a large TSO/E account might want to suppress the SMF dynamic DD records (type 40).
Check resource use during a specific interval. For example, select records during the peak workload period.

Defining the Exit in SMFPRMxx

In the SMF parmlib member (SMFPRMxx), specify IEFU83 on the EXITS option of either the SYS or SUBSYS parameters, depending on the scope of work (system-wide or subsystem-wide) the exit is to affect.

If you use the SUBSYS option, the system invokes the IEFU83 routine only for work running under the subsystems you specify on SUBSYS. If you use the SYS option, the system invokes the IEFU83 routine for work running under any SMF-defined subsystem, such as JES2, JES3, STC, ASCH, OMVS, or TSO.

For more information about coding the EXITS option, see the description of SMFPRMxx in z/OS MVS Initialization and Tuning Reference.

Controlling the Exit Routine Through the Dynamic Exits Facility

IBM® has defined the IEFU83 installation exit to the dynamic exits facility. You can refer to the exit by the name SYS.IEFU83 or SYSyyy.IEFU83. See the description of the SMFPRMxx parmlib member in z/OS MVS Initialization and Tuning Reference for an explanation of the naming conventions for SMF exit routines. You can use the EXIT statement of the PROGxx parmlib member, the SETPROG EXIT operator command, or the CSVDYNEX macro to control this exit and its exit routines.

To define IEFU83 to the dynamic exits facility, you must specify the exit in both PROGxx and SMFPRMxx. The system does not call the exit if it is defined in PROGxx only. If you do not plan to use the dynamic exits facility for this exit, you need only define IEFU83 in SMFPRMxx.

If you do not associate any exit routines with exit IEFU83 in PROGxx, the system defaults to using the exit routine name that matches the exit name (IEFU83).

If you associate exit routines with this exit in PROGxx, the system does not use the default exit routine. If you need the default exit routine, you should explicitly add it to PROGxx.

You can use the ADDABENDNUM and ABENDCONSEC parameters on the CSVDYNEX REQUEST=ADD macro or the ABENDNUM parameter of the SETPROG EXIT operator command to limit the number of times the exit routine abnormally ends before it becomes inactive. An abend is counted when both of the following conditions exist:

The exit routine does not provide recovery, or the exit routine does provide recovery but percolates the error
The system allows a retry; that is, the recovery routine is entered with bit SDWACLUP off.

By default, the system disables the exit routine after two consecutive abends.

Exit Routine Environment

IEFU83 receives control in the following environment:

Enabled for interrupts.
In supervisor state with PSW key 0.
In AMODE 31.

Exit Recovery

If IEFU83 abnormally terminates, SMF, in most cases, does not terminate. SMF deactivates the exit and then issues message CSV430I to the operator. If the exit performs a critical function, the operator can issue a SET SMF or SETSMF command to terminate recording. Otherwise, SMF recording continues but bypasses the installation exit routine.

IBM strongly recommends that you set up an ESTAEX recovery routine to handle errors that might occur during the execution of your exit routine.

An ESTAE-type recovery routine is set up by the module that calls IEFU83; the recovery routine, if it gets control, will prevent SMF from ending if the exit routine abnormally ends. If this recovery routine gets control on two consecutive invocations of the exit, SMF requests that the exit routine be marked inactive, preventing any further invocations of that exit routine. The system issues message CSV430I, naming the exit and the exit routine.

If the exit performs a critical function, the operator can issue a SET PROG or SETPROG MODIFY command to change the status of the exit to active. This should be done only if you have corrected the program, or if you know the error conditions are transient.

Whether or not the exit routine continues to be invoked depends on the abend processing of the dynamic exits facility.

Exit Routine Processing

Each SMF record is passed to an installation exit (either IEFU83, IEFU84, or IEFU85) before it is written to the SMF data set. If you use the SMFWTM macro, or if you specify BRANCH=NO on the SMFEWTM macro, SMF invokes installation exit IEFU83. If you use the SMFEWTM macro and specify BRANCH=YES, SMF invokes installation exit IEFU84.

IEFU83 places a return code in register 15 before returning control; the code indicates whether the record should be written to the SMF data set.

Programming Considerations

IEFU83 must be reenterable and refreshable, because PLPA pages are stolen. That is, they can be paged in but not paged out, and subsequent page-ins overlay any code changes.

If IEFU83 is entered for a foreground job, it cannot access installation-defined data sets. If the exit is entered for a background job, it cannot write to installation-defined data sets.

The addresses of the user communication and user identification fields of the common exit parameter area (a copy of the first 36 bytes of the JMR) are not passed to the IEFU83 exit routine. To obtain these addresses, the exit routine can follow pointers from the PSA to the TCB to the JMR. In the PSA, the PSATOLD points to the TCB. In the TCB, the TCBTCT field points to the TCT. In the TCT, the TCTJMR field points to the JMR. The JMR and the PSA are mapped by macro IEFJMR and IHAPSA, respectively. See z/OS MVS Data Areas in z/OS Internet Library at http://www.ibm.com/systems/z/os/zos/bkserv/ for the mapping of the JMR and the mappings of the TCB and the TCT.

APPC/MVS Consideration: You might want your exit routine to perform specific processing for work initiated by the APPC/MVS transaction scheduler. To enable your exit routine to determine when it has been invoked during this type of processing, have the routine check the OUCBSUBN field in the OUCB control block. For APPC/MVS TPs, this field is set to 'ASCH' (EBCDIC).

The exit routine can access OUCBSUBN by chaining through pointers from the PSA to the ASCB to the OUCB. In the PSA, the PSAAOLD points to the ASCB. In the ASCB, the ASCBOUCB field points to the OUCB.

The ASCB, OUCB, and the PSA are mapped by macros IHAASCB, IRAOUCB, and IHAPSA, respectively. The mappings are described in z/OS MVS Data Areas in z/OS Internet Library at http://www.ibm.com/systems/z/os/zos/bkserv/.

Macro Instructions and Restrictions: When issuing a WTOR macro, specify LONG=YES on the WAIT macro.

IEFU83 cannot use the SMFWTM or SMFEWTM macro to write to the SMF data set.

Entry Specifications

SMF passes to IEFU83 the address of a fullword that points to the SMF record.

Registers at Entry: The contents of the registers on entry to the exit are as follows.

Register: Contents
0: Not applicable
1: Address of the parameter list.
2-12: Not applicable
13: Register save area
14: Return address
15: Entry point address of IEFU83

Parameter Descriptions: Register 1 points to the following address:

Word 1: The address of the record that SMF is to write. The first four bytes of this record are the record descriptor word (RDW). See z/OS MVS System Management Facilities (SMF) for a description of the RDW.

Figure 1. IEFU83 Input Parameter Structure

Return Specifications

A return code from IEFU83 indicates whether the current SMF record is to be suppressed.

If you associate multiple exit routines with IEFU83, you can specify how the return information is to be handled using the ATTRIB KEEPRC function of the SETPROG EXIT command, the EXIT statement of PROGxx, or CSVDYNEX services. If multiple exit routines match the ATTRIB KEEPRC criteria, the system returns information from the exit routine that finished first.

If you do not specify the ATTRIB KEEPRC function, the system returns the information from the exit routine whose return value was the greatest. If multiple exit routines return with the same highest value, the return information from the exit routine that finished first will be returned.

If you associate multiple exit routines with exit IEFU83, and any of those exit routines return with a value of 4, the current SMF record is suppressed.

Registers at Exit: Upon return from the exit processing, the register contents must be as follows.

Register

Contents

1

Not applicable

2-14

Not applicable

15

One of the following return codes:

Return Code: Explanation
4: SMF is not to write the record to the SMF data set.
Other than 4: SMF is to write the record to the SMF data set.