PMRM Active User Task Detail wait ECB SPACE

Products

• IDMS
• IDMS - Database

Issue/Introduction

In IDMS Performance Monitor realtime monitor (PMRM) Active User Task Detail screen, if a task is in a WAIT state it will show the ECB(s) that the task is waiting for. One of these ECBs is "SPACE". What does this mean?

Environment

Release: All supported releases.
Component: Performance Monitor.

Resolution

ECB type SPACE means Page Space Lock. 

If a task indicates it is waiting for ECB "SPACE", there will also be a "waited-on DBKEY" indicating line number 0 which is the SR1 record in the database page header.

 
Example:  10030095:0  

When a transaction needs to STORE or ERASE a record on a page, or perform a MODIFY on a variable length record that changes record length, the transaction must first acquire a lock on the page space available count, then it can do the update to the record and once the update operation is complete the page space lock is freed.

 

Update locks on any records updated are held until COMMIT or FINISH, but page space locks are freed as soon as the update operation completes.