When a job is waiting for a resource, it may wait in main storage or else be removed from main storage until the resource becomes available. A job waiting for a system resource may have the following wait states:

• Short wait
• Short wait extended
• Long wait

A job in this wait state holds an available activity level while waiting for an activity to occur. A job can remain in short wait for a maximum of two seconds. Actions that cause short waits include:

• Sending break messages to workstations.

When using remote lines, avoid actions that cause short waits since they can cause the wait time in main storage to be much longer for a job than if the job was waiting for resources at a local workstation.

A job moves to this wait state after being in a short wait for the maximum two seconds. If no activity occurs within this time, the system cancels the short wait, removes the job from the activity level, and puts the job into a long wait. In the performance reports, this job state transition is called a short wait extended.

A job that immediately leaves the activity level is in what is called a long wait. During a long wait, the job leaves the activity level.

Examples of long waits are:

• Key/think waits
  This type of long wait occurs outside the activity level when a job completes its work assignment and returns to request more work. It is a user-defined time period allowing the user to decide what is to be entered and to type the data. When the job receives the new assignment, it attempts to run again. If no activity level space is available, the job becomes ineligible.

• record lock conflicts
  These occur when two or more jobs attempt to lock the same record of a file.

• Distributed Data Management data requests