SSC, Inc.



Select a library from your LINKLIST concatenation, where you would like the IEAVMXIT to reside. Verify that no module exists already with this name, to include in SYS1.LINKLIB. Try to select a LINKLIST library that will be used across new releases of MVS to make migration an easier task.

To activate the IEAVMXIT exit at IPL, specify the following in the CONSOLxx member in SYS1.PARMLIB:


The IBM supplied Installation Exit IEAVMXIT (described in detail in the IBM manual, Installation Exits, SCxxxx-xx-xx) is the vehicle for capturing and processing messages. IEAVMXIT gets control for every WTO (Write to Operator) and WTOR (Write to Operator with Reply) that is issued on an MVS system. The IEAVMXIT provided consists of two parts, which include: the executable code that performs a particular action and a Message Table that defines what messages to process and how to process them. The executable portion of the exit is never modified, so the introduction of any errors into the exit are greatly minimized. An ISPF/REXX interface to define the messages that you wish to process and automate, is supplied with the exit. With this interface you can dynamically add entries to the table, and immediately make available for exit processing

Even though the IEAVMXIT is invoked for every WTO/WTOR issued by MVS, the impact on the operating system and applications is minimal. The exit searches the Message table against the system supplied message ID, and if no match is found then IEAVMXIT exits without having performed any other functions (e.g. GETMAIN to acquire storage). Further filtering is built into the Message Table entries to either select or exclude based on a search argument. All efforts have been made to build efficiency, functionality and flexibility into this one exit.

The use of the IEAVMXIT exit, coupled with how you define the messages to be processed will allow you to perform automation of activities on your system. The IEAVMXIT program will perform certain functions directly from the exit, to include: reply to outstanding WTORs, and issue commands directly to MVS. In the instances where further processing is necessary to support your system, the exit will issue either an MVS Start command, and pass the message to a Started Task (STC), that will invoke a REXX EXEC to process the message.


The following is an example of the ISPF Panel presented for adding WTOs and WTORs to the Message processing table that is linked with the IEAVMXIT.


------------------------------------- Automated Operations -----------------------------------

Add WTO/WTOR Messages for Automated Operations Processing

Message ID ==>
Enter up to 20 characters of the Message you wish to process

Action to Perform ==>
Valid Actions are REPLY, COMMAND, or EXEC

Reply ==>
If Action was REPLY then specify the REPLY to the Message
Command ==>_COMMAND
If Action was COMMAND then specify the COMMAND to issue

Search Argument ==>
(Single Quotes are not allowed in Search Argument )
Select if Argument Found ==> Exclude if Argument Found ==>

Process Multi-Line WTO (Y/N) ==>
PF1 - Help/Description of Facility PF3 - End/Assemble

Depending on your level of MVS, you can dynamically refresh the IEAVMXIT when adding entries, using the following sequence of commands:

K M,UEXIT=N to disable the exit
F LLA,UPDATE=xx where xx is the suffix of a SYS1.PARMLIB CSVLLAxx entry where IEAVMXIT resides.
F LLA,REFRESH will work, though it is less efficient.
K M,UEXIT=Y to enable the exit

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Last Updated: 26 March 2020
Bill Sweeney /