Skip to Main Content
IBM Data and AI Ideas Portal for Customers

Shape the future of IBM!

We invite you to shape the future of IBM, including product roadmaps, by submitting ideas that matter to you the most. Here's how it works:

Post your ideas

Post ideas and requests to enhance a product or service. Take a look at ideas others have posted and upvote them if they matter to you,

  1. Post an idea

  2. Upvote ideas that matter most to you

  3. Get feedback from the IBM team to refine your idea

Help IBM prioritize your ideas and requests

The IBM team may need your help to refine the ideas so they may ask for more information or feedback. The product management team will then decide if they can begin working on your idea. If they can start during the next development cycle, they will put the idea on the priority list. Each team at IBM works on a different schedule, where some ideas can be implemented right away, others may be placed on a different schedule.

Receive notification on the decision

Some ideas can be implemented at IBM, while others may not fit within the development plans for the product. In either case, the team will let you know as soon as possible. In some cases, we may be able to find alternatives for ideas which cannot be implemented in a reasonable time.

Additional Information

To view our roadmaps:

Reminder: This is not the place to submit defects or support needs, please use normal support channel for these cases

IBM Employees:

The correct URL for entering your ideas is:

Status Under review
Workspace Db2 for z/OS
Created by Guest
Created on Apr 22, 2022

Cross-Invalidation due to pcloset/p-lock negotiation avoidance

Problem Statement / Pain points :

  • Whenever there is no R/W activity and PCLOSET threshold is reached, pagesets SWITCH OUT of GBP dependency and the pages in our Bufferpools are cross-invalidated . Thereafter when R/W starts again, pagesets SWITCH IN to GBP dependency and the pages in Bufferpools are cross-invalidated "again".

  • This repeated invalidation behavior because of going in and out of GBP-dependency is painful for our business critical applications. These applications depends on HUGE indexes which are expected to be 50-80% 'in memory' . This invalidation behavior due to PCLOSET or PLOCK negotiations defeats the purpose of having HUGE bufferpools and drastically increases SYNCREADs impacting online workload performance.

Workaround considered :

  • Increased ZPARM PCLOSET value (which comes with extra logging and 'recovery & restart time' implications )

  • Requested application team to schedule dummy SQL (partition-level inserts that rollbacks) every x minutes less than PCLOSET to keep a particular object in a desired GBP-dep state all through the day. Application team are concerned and hesitant to implement dummy SQLs against production data.

Proposed Solutions to IBM :

  • PCLOSET option to be made available at Tablespace and Indexspace level .

  • If PGSTEAL(NONE) - VSEQT(100) like behavior is available for PGSTEAL(LRU/FIFO) it will solve our issues. We understand PGSTEAL(NONE) - VSEQT(100) keeps the bufferpool pages "refreshed / implicitly prefetched " even after getting cross-invalidated because of PCLOSET or PLOCK negotiations.

  • More options to customize PGSTEAL(NONE) which will make it flexible to accommodate table/indexes which cannot fit entirely in the BP. Currently we understand PGSTEAL(NONE) is useful only for objects that fit entirely in the Bufferpool.

Needed By Month