If your users notice slow performance in running queries or formatting reports, the problem might be that QMF is attempting to retrieve all the database rows requested during one command before starting another. It is also possible that the user does not have enough virtual storage to retrieve all the requested rows. This section explains what you can do to solve each kind of problem.
Users might also experience slow performance if they do not have enough virtual storage to accommodate a large report. For example, if you set the DSQSBSTG parameter at a very low value and the user runs a query that retrieves hundreds of thousands of rows, QMF can only maintain a small amount of data in user memory. The user might find performance slow for formatting complex reports or scrolling the report.
To maximize report performance, make sure you specify an adequate amount of virtual storage for the user, using the DSQSBSTG or DSQSRSTG parameter.To provide the best performance, use a value that accommodates the largest report the user is likely to have.
You can also define a spill file for the user. However, using primarily virtual storage for QMF operations provides better performance. Users who rely on a spill file and have little virtual storage might notice slow performance for large reports. For CICS, because a spill file can hold a maximum of 32, 767 rows of size 4K each, setting DSQSBSTG higher ensures that QMF will complete the report.
Even with a spill file, a user can encounter the incomplete data condition. If this occurs often, you might want to find if there is an additional problem.
QMF performance may also slow down if QMF needs a data row (as a result of a SCROLL BACKWARD command) and that data is not in the spill file or in virtual storage.
Setting the DSQSRSTG parameter at a very high value can also cause slow performance.
If the problem is caused by a lack of available space on the volumes of a control table storage group, add more volumes to this storage group with the DB2 ALTER STOGROUP query. For a description of this query, see the DB2 UDB for OS390 SQL Reference manual.
If a QMF transaction runs out of virtual storage in the CICS region, the transaction might time out waiting for storage to become available. These recommendations are in addition to any storage required by additional products installed.
There are no additional concerns on VM.
Follow these instructions for increasing the CICS region on VSE.
If a QMF transaction runs out of virtual storage in the CICS region, the transaction might time out waiting for storage to become available. These recommendations are in addition to any storage required by additional products installed.
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