When either the SOURCE, LIBRARY, PUNCH, or OBJECT exit is invoked for a READ, WRITE, or PROCESS request, the assembler sets the buffer length to 80.

On z/OS and CMS, if you specify the GOFF assembler option, and the OBJECT exit is invoked, the buffer length might be fixed-length 80, or variable-length, depending on the JCL (z/OS) you supply. The maximum value for variable-length records is 8212.

For an OPEN request the LISTING exit can use this field to pass the listing line length to the assembler. The exit indicates that it has provided a print line length by setting the return code to 0 and the reason code to 4.

z/VM and z/OS

The line length must be in the range 121 to 255. If it is any other value, the assembler issues message ASMA402W and does not call the exit to process listing records.

z/VSE

If the assembler opens the listing data set and the LISTING exit provides a print line length, the line length must be 121 if SYSLST is assigned to disk, otherwise it can be any value from 121 to 133. If it is any other value, the assembler issues message ASMA402W and does not call the exit to process listing records.

For all other calls to the LISTING exit, the assembler sets this field to the length determined during the OPEN call.

The TERM exit can use this field to indicate to the assembler the length of the terminal record. This indication is done when the exit is invoked with an OPEN request. The exit indicates that it has provided a terminal line length by setting the Return Code to 0 and the Reason Code to 4. The value must not be zero, or negative, and must not be greater than 255 on z/OS and CMS, or 125 on z/VSE. If the value is not correct, the assembler issues message ASMA404W and does not call the exit to process terminal records.

For all other calls to the TERM exit, the assembler sets this field to the length determined during the OPEN call.