Job characteristics

Work management provides a way for you to control the work done on your system through a job's attributes. However, before you can control the various aspects of a job, you need to understand the different characteristics of a job.

The following information describes the characteristics of jobs:

• Job name syntax
  To make it easier to control and identify jobs on the system, each job has a unique qualified job name. The qualified job name consists of three parts: the job name (or simple job name), the user name, and the job number.
• Job Attributes
  Job attributes determine how the system runs each job. Some job attributes are set from the user profile. Other job attributes come from system values, from locales, from a Submit Job (SBMJOB) command, from a job description, and from the Change Job (CHGJOB) command (from which you can change values for attributes while the job is running).
• Job description
  The job description allows you to create a set of job attributes that are saved and available for multiple uses. The job description can be used as the source for some of the job attributes that tell the system how to run a job. The attributes tell the system when to start the job, where to get the job from, and how the job will run. You can think of a job description as a template that many jobs can use, thereby reducing the number of specific parameters that you need to set for each individual job.
• Job descriptions and security
  Every job in the system uses a job description during job initiation. This controls the various attributes of a job. The USER parameter controls the name of the user profile assigned to the job. A job description that has a user profile name (USER) specified should be authorized only to specific individuals. If not, at security level 30 and below, other users will be able to submit jobs to run under that user profile.
• Call stacks
  The call stack is the ordered list of all programs or procedures currently running for a job. The programs and procedures can be started explicitly with the CALL instruction, or implicitly from some other event.
• Class object
  A class object contains the run attributes that control the run-time environment of a job. IBM-supplied class objects, or classes, meet the needs of both typical interactive and batch applications. The following classes (by name) are supplied with the system:
• Job user identity
  The job user identity (JUID) is the name of the user profile by which this job is known to other jobs. This name is used for authorization checks when other jobs attempt to operate against this job.
• Job user identity examples
  This topic contains examples that will help you to better understand how the job user identity (JUID) is assigned in different situations.
• Threads
  The term thread is shorthand for "thread of control". A thread is the path taken by a program while running, the steps performed, and the order in which the steps are performed. A thread runs code from its starting location in an ordered, predefined sequence for a given set of inputs.
• Locked objects
  Jobs and threads use objects to process work.