Queue Dataset

The queue dataset enables the session manager to preserve and restore requests across initial program loads of MVS. The session manager maintains the current highest request number and the log history in the queue dataset. After an IPL, Strobestarts numbering new requests by increasing the saved request number by one.

The session manager updates the queue dataset each time a request is added or modified. If an IPL occurs before a request has been processed, the request is re-created when the Strobeenvironment is established after the IPL. The session manager removes requests from the queue only when they exceed their retention period or when a user deletes them.

Queue Dataset Processing Considerations

When you initialize the Strobeenvironment, Strobeverifies that the dataset allocated to the data definition name SYSQUEUE exists and is a VSAM dataset. Strobeterminates if it determines that the dataset does not exist or is not a VSAM dataset.

Use the same queue dataset for all systems that share DASD in a complex. Each session manager operates independently of the others through a unique identifier for each system.

Multisystem Considerations for the Queue Dataset

In a multisystem environment, the queue dataset is a central repository for all Strobemeasurement requests in the XCF-group. Each instance of Strobemaintains its own copy (the local work queue) of the requests contained in the queue dataset. It keeps the local work queue current by reading the new or changed information in the queue dataset and updating the local work queue whenever it receives an XCF signal indicating that the queue dataset has changed.

Queue Dataset Characteristics

The queue dataset is a VSAM key-sequenced dataset. If you need to reallocate the dataset, do so when the Strobeenvironment does not exist. The dataset is defined at install time through the IBM utility IDCAMS with the attributes shown in the following figure.

Queue Dataset Characteristics

Managing the Queue Dataset

Use the following commands to manage the Strobe queue dataset. The full syntax for these commands is provided in Controlling Strobe with Administrative Commands in ISPF.

• STATUS
• SHOW QUEUE
• CLEAN
• LIST.

To view the characteristics of the queue and other datasets, issue the following command from the operator’s console:

    MODIFY STRxSM,SHOW QUEUE

Strobedisplays the following information:

• Dataset name
• Percentage of space used
• Number of extents
• RBA statistics
• Available FREE SPACE
• Number of records inserted, updated, and deleted
• Number of control interval and control area splits
• Number of records in the dataset.

Checking Queue Dataset Status

Use the STATUS command to determine the amount of space remaining in the Strobequeue dataset. Alternatively, look in the log, which provides STR6193I messages about the size of the dataset contents. When you customize the StrobePARMLIB member during installation, use the MAXREQ parameter to establish the maximum number of requests allowed in the queue dataset. If you are using AutoStrobe, these requests include queued, completed, active, and deferred requests. The default number of requests allowed is 200. Strobeissues a warning message with each request whenever the queue size has reached 75% of the maximum value and accepts no further requests after the maximum is reached.

To determine the number of requests, invoke the STATUS command or the SHOW QUEUE command. Then issue the CLEAN command to remove completed requests, queued requests, or both, based on the number of days these requests have been on the queue.

Expanding the Queue Dataset

Periodically, you may need to reorganize or expand the dataset, as follows:

1. Delete all unwanted requests.
2. Stop Strobe.
3. Reorganize or expand the dataset.
4. Restart Strobe.

Deleting all Queued Requests

To delete all queued requests, regardless of how long they have been on the queue, use the following command:

Deleting Specific Requests

To delete specific request categories, first issue the LIST command (with specific arguments) and then issue the CLEAN command (with the same arguments). For example, to target requests queued for four or more days and requests that have been completed for three or more days, and then to delete those requests, use the following commands:

Synchronizing the Queue Dataset

In a multisystem environment, XCF communications occasionally fail. If this happens, internal representations of requests can lose synchronization with their counterparts on the queue dataset. For example, a request marked Completed on one member of the StrobeXCF group is marked Queued on another. Message STR6814E alerts you to this problem.

You can correct the problem in either of the following ways:

• Issue the RESYNC command, specifying the request number of the problem request. You can issue this command from any system in the StrobeXCF group. For example, to refresh request number 453 with information from the queue dataset, enter
  .RESYNC 453
• Stop all members in the Strobe XCF group and restart Strobe as described in Stopping a Strobe XCF Group.