Applications can decrease the turn-around time of large amounts of printed outputs that jobs create by specifying the SEGMENT= parameter on the DD JCL statement that defines the output for line mode data. SEGMENT= forces JES2 to spin off output after producing a specified number of pages. There will be a segment identifier on the separator page for each segment if segmentation is in effect. See z/OS MVS JCL Reference for more information on specifying the SEGMENT= parameter.

Segmenting output into many small pieces, however, could cause performance problems as each segment requires an output group to represent it. Specifying SEGLIM= on the OUTDEF initialization statement minimizes the impact output segmentation has on your installation. When the number of segments a job creates for any piece of output exceeds the SEGLIM= value, JES2 stops segmenting the output and prints the remaining output as one segment. See z/OS JES2 Initialization and Tuning Reference for additional information about the OUTDEF statement.

If a SYSOUT data set is segmented, each segment is treated as a separate file for printing, punching, or NJE transmission. Output segmentation can be used to make portions of the SYSOUT data set available earlier for processing or transmission before the job completes or before the entire data set is available. For NJE transmission, this can also improve line utilization by reducing the time to retransmit files over NJE should there be a line failure or other unrecoverable error.