Defining Spool Space Allocation Units

The basic unit of spool space allocation is called a track group. A track group is a group of spool records, with the size of each spool record equal to the size of a JES3 buffer. JES3 buffer size is defined by the BUFSIZE parameter on the BUFFER initialization statement You can define the number of spool records in a track group using the GRPSZ parameter on the BUFFER statement or on the SPART statement.

JES3 allocates one or more track groups to a job when the job needs spool space. The number of track groups allocated on each request depends on the number defined using the TRKGRPS parameter for the job's SYSOUT class, //*MAIN JES3 control statement, job class, or assigned processor.