OBJECT (z/OS and CMS) and PUNCH exit processing

When you specify the OBJEXIT suboption of the EXIT assembler option, the assembler calls either the PUNCH user exit or the OBJECT user exit, or both, as follows:

z/VM and z/ OS

If you specify the OBJECT assembler option, the assembler calls the OBJECT user exit.
If you specify the OBJECT and the DECK assembler options, the assembler calls the user exit as a PUNCH exit, and then as an OBJECT exit.

If you specify the DECK assembler option, the assembler calls the PUNCH user exit.

You can use the exit to override the effect of the DECK or OBJECT assembler options. The exit does this by indicating to the assembler that it opens the output data set and does all the output processing. Then, as each object record is passed to the exit, the exit can decide whether to write the record, and where to write the record. For instance, the exit can write the records to a different data set than the assembler normally writes them.

z/VM and z/ OS: The exit is not called if you specify the NODECK and NOOBJECT assembler options.
z/VSE: The exit is not called if you specify the NODECK assembler option.

If you want to process the object records in the exit, but you do not want the assembler to write the records to the normal output data set, you can do one of these actions:

Instruct the assembler to discard the records by setting the exit return code.
Suppress the object output by doing this action:
z/OS

Provide a //SYSLIN DD DUMMY JCL statement, and a //SYSPUNCH DD DUMMY JCL statement.

CMS

Issue a FILEDEF SYSLIN DUMMY command, and a FILEDEF SYSPUNCH DUMMY command.

z/VSE

Assign SYSPCH to IGN.
Instruct the exit to issue an OPEN return code of 4.

The assembler calls the OBJECT and PUNCH exit with the following request types: