Craig S. Mullins
Database Performance Management

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Winter 1999

The Buffer Pool
By Craig S. Mullins
“The Buffer Pool” will be a regular feature of PLATINUM SYSJOURNAL. The purpose of this column is to disseminate tips, tricks,  techniques, rumors, and all-purpose information about DB2 for OS/390. If you have anything to contribute, please e-mail me at

There’s APARty Going On!

Is there a favorite feature of Version 6 of DB2 for OS/390 that you simply cannot wait to have? Well, many of the new features announced for V6 are being added to V5 via APARs. So you might not have to wait until V6 becomes generally available (due in June 1999)! For example, APAR #PQ15682 allows DB2 utilities to be run as a WLM-managed stored procedure. And APAR #PQ18543 increases the DSMAX limit to be greater than 10,000.

You can check for yourself what new functionality has been added to DB2 through APARs by going to IBM’s web site. The following URL provides the details:

The Early SQLJ Bird Gets the Worm!

In a related news byte, SQLJ support was announced for DB2 V6, but IBM has announced early availability of SQLJ support in DB2 V5 via APAR #PQ19814. SQLJ complements JDBC to enable both static and dynamic SQL in Java code. JDBC is dynamic; SQLJ is static. For more information or to download SQLJ, visit:

Reorganizing the DB2 Catalog

It has been possible to reorganize the DB2 Catalog table spaces using the REORG utility since DB2 V4. But don’t go overboard and spend too much time here! I mean, you had no REORG capability on the system catalog for more than a decade and your DB2 subsystems survived. I’d recommend reviewing the DB2 Catalog for reorganization no more than once a year unless you have made huge changes to your DB2 environment that could have impacted the system catalog table spaces. For example, adding a large number of new DB2 databases or applications could cause inefficiency in the DB2 Catalog.

The DB2 Mailing List

Everyone with an interest in DB2 for OS/390 should belong to the DB2-L mailing list. Simply by subscribing to the mailing list, pertinent information is sent directly to your email in-box. Postings will begin to arrive in your email box from a remote computer called a list server. The information that you will receive varies - from news releases, to announcements, to questions, to answers. Be careful, though, because much of it is just other users’ opinions and not the gospel from IBM. Users can send and respond to DB2  mailing list messages. Responses are sent back to the list server as email, and the list server sends the response out to all other members of the mailing list. To subscribe to the mailing list, simply send an email to the appropriate subscription address, requesting a subscription. In the case of the DB2 mailing list, the subscription address is LISTSERV@RYCI.COM. The message should read as follows:


After issuing the preceding command, the list server will send you a message asking you to confirm the subscription. When you do, information will quickly begin flowing into your email box (perhaps at a much quicker rate than you can reasonably absorb). Literally, hundreds of messages may be sent to you every week. To sign off of the mailing list, simply send the following message to the same subscription address:


Because of this volume, I also recommend digesting your DB2 mailing list emails. A digest is an accumulation of the day’s messages sent as one big email. The benefit of digesting is that instead of receiving multiple daily messages from a mailing list, only one daily digest is sent. Because the DB2 list is usually quite active, you may receive dozens of emails daily if you don’t choose the digest option. To request digesting, send an email to the subscription address. The digest request must be made after you have successfully subscribed to the mailing list. For the DB2 mailing list, send the following message to the subscription address:


There are drawbacks to digests: threads can be hard to follow, it is more difficult to respond to messages, and the digest can become quite large. But the benefit of getting just one message a day usually outweighs the negatives!


Craig S. Mullins

Thank you for reading this installment of “The Buffer Pool.” And remember, we want to make this column your place to go for the scuttlebutt on DB2 for OS/390. So contact us with any tips, tricks, techniques, or rumors. See you next issue! 

(Actually, this was my last article for PLATINUM technology… Shortly after publication PLATINUM was acquired by CA and I left the company.  I will not be writing The Buffer Pool for SYSJOURNAL any longer.)


© 1999 Craig S. Mullins,  All rights reserved.