PURPOSE: The RECORD LOCKS option controls whether access requests to a Data Set (DS) are queued or not. This command is valid in a CM, SF and as a direct command. It is not valid in a PM.
{ENABLE; DISABLE} RECORD LOCKS [{IF; UNLESS} clause]
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ENABLE |
sets up the Simple Queued environment for DS access. When more than one user tries to access a DS, their requests are queued in the order they are received. It allows for multi-user input and single user updating. The queuing is done only on the record level (unlike the Concurrent Queued environment which queues at both the record and table levels). |
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DISABLE |
returns DS accessing to the default environment. This is the default state. |
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{IF; UNLESS} clause |
specifies a condition for the option to be enabled or disabled. |
*ENABLE RECORD LOCKS
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.
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*DISABLE RECORD LOCKS
NOTES: The following table illustrates Data Set (DS) accessing with RECORD LOCKS enabled for all users (assuming no other queued environments are established by any of the users).
| JOB | ACCESS FOR: | DATA SET IS: | JOB IS: |
| 1 | Update | open | running |
| 2 | Input | open | running |
| 3 | Input | open | running |
| 4 | Update | open | queued |
| 5 | Input | open | queued |
| 6 | Supersede | busy | waiting |
| 7 | Input | open | queued |
Simple Queued Environment
All the jobs requested access to the same DS. The request order is reflected by the job numbers. While Job 1 has the Data Set opened for update, only Jobs 2 and 3 can concurrently access it for input (reading data).
Job 4 has successfully opened the Data Set and is queued. It will only be allowed access when Job 1 releases the DS, since job one has exclusive use for updating.
Jobs 5 and 7 could run concurrent with Job 1 but cannot "jump" past Job 4. They are queued and will start when Job 4 starts.
Job 6 is attempting to supersede the DS. ACCENT R does not queue this request. (Job 7 appears right behind Job 5 in the queue.) Job 6 must wait and try again periodically until all jobs (including new ones that may come in before the current jobs in the queue finishes) release the DS. Once Job 6 has access, no other job can open the DS until the supersede is finished.