OPEN

The assembler calls the exit with a request type of 1 (OPEN) at the start of the assembly.

The exit sets the return code in the Exit Parameter List to one of these values:

0

Instructs the assembler to open the listing data set, and supply the listing output records to the exit in later PROCESS calls.

The exit can set the record length for the listing data set by setting the reason code to 4 and the buffer length field.

Note: A reason code of 16 indicates a REINIT call is required.

z/VM and z/OS: The buffer length field can be set to any value from 121 to 255. If the listing data set has a variable-length record format, the LRECL assigned is 4 bytes greater than the value the exit returns. If the value is less than 121 or greater than 255, the assembler issues message ASMA402W and does not call the exit for any further processing.
z/VSE: The buffer length field can be set to any value from 121 to 133. If the value is less than 121 or greater than 133, the assembler issues message ASMA402W and does not call the exit for any further processing.
If you assign SYSLST to a disk data set in your JCL, the record length must be 121.

The buffer length field can be set to any value from 121 to 255. If the listing data set has a variable-length record format, the LRECL assigned is 4 bytes greater than the value the exit returns. If the value is less than 121 or greater than 255, the assembler issues message ASMA402W and does not call the exit for any further processing.

The buffer length field can be set to any value from 121 to 133. If the value is less than 121 or greater than 133, the assembler issues message ASMA402W and does not call the exit for any further processing.

If you assign SYSLST to a disk data set in your JCL, the record length must be 121.

4

Indicates that the exit writes the listing records in later WRITE calls. If you want to provide the assembler with the values for the system variables &SYSPRINT_DSN, &SYSPRINT_MEMBER, and &SYSPRINT_VOLUME, the exit must set the reason code to 4 and place the values in the data set name, member name, and volume serial fields of the exit-specific information block. The assembler also shows this information in the Diagnostic Cross Reference and Assembler Summary section of the listing, and includes it in the associated data file Output File Information record.

Note: A reason code of 16 indicates a REINIT call is required.

16

Instructs the assembler to open the listing data set, and make no further calls to the exit.

The assembler sets the linecount field to the value of the LINECOUNT assembler option. This value is the number of lines per page in the listing. The exit can change the line count to a value of 0, or any value from 10 - 32767. LINECOUNT describes the LINECOUNT assembler option.

If you provide a character string in the str3 suboption of the EXIT assembler option, the buffer pointer field points to the character string, and buffer length contains the length of the character string. The buffer length is set to zero if there is no character string.