To optimize the use of print/punch devices, JES2, or the user, groups a job's output data sets together based on similar output characteristics. Data sets must agree on class, destination, writer name and process mode characteristics to be grouped together. These characteristics are called grouping characteristics. Each of these output groups is represented by a job output element (JOE), which is the smallest unit of a job's output that JES2 selects for output device processing.

An output group has three identifiers (for example, group10.1.2). The first identifier is the group id. This is a 1 to 8 character alphanumeric name that the user can specify in the JCL. If the user does not specify a name, JES2 will generate one. The name refers to the collection of data sets that JES2 grouped together because their grouping characteristics matched.

The second identifier distinguishes between job output elements of the same group. Job output elements may have the same group id when JES2 constructs more than one job output element for the group because class, destination, writer, and/or mode were not identical within the group, or because device setup characteristics were not identical within the group and your installation does not permit demand setup job output elements (that is, job output elements that require more than one device setup).

The third identifier is used to distinguish between copies of the same job output. Multiple copies of the same job output may result from job copies (COPIES= on the output JCL statement) or the $N command.

Qualifying the output group name with a job output element identifier allows you to address, and thus control the job output element.

JES2 commands allow you to control various aspects of the job processing cycle by addressing the data by output group name, with or without a job output element identifier. You can set the output characteristics for one or all of the job output elements in a job, or range of jobs using the $T O command. You can also display the output processing characteristics of designated output groups or individual job output elements (JOEs) using the $DO job command and cancel specific output groups or JOEs created by a job.