CA IDMS DC001000 deadlocks on the space management lock on a page
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CA IDMS DC001000 deadlocks on the space management lock on a page


Article ID: 16440


Updated On:




In the CA IDMS log getting error messages like this:

DC001000 Vnn Tnn T:nn taskid P:progname C:DEAD WAITING ON R:LTXNLOCK 00002008 nnnnnnnn

The documentation for message DC01000 indicates the x'20' in the third byte means this is a deadlock on a space management lock and nnnnnnnn is a page number.

What causes a deadlock on the space management lock on a page?


Release: 19.0
Component: CA IDMS/DB


When a program performs an update which causes the space available count on the page to change we put a lock on the space management for that page. The space available count is stored in the header of each database page in the SR1 system record which is pointed to by line index 0.

Note, this is not a lock on the Space Management Page (SMP) in the area, IDMS does not place locks on SMP pages.

These types of deadlocks can be caused by:

  • Programs updating records but not doing a COMMIT often enough or not doing COMMITs at all. 
  • Database design problems causing the same record to be updated concurrently by multiple tasks. 

Adding  DEADLOCK_DETAILS=ON  to the SYSIDMS parameters in the CV will produce more deadlock information when it occurs in message DC001001. It will show the transaction/rununit ID, the program name and the subschema name.

Analyze the pages where the deadlocks occur and the record types that reside in them. 

Then examine how the programs are using those records.

You can avoid deadlocks in the DDLDCRUN queue area by increasing the page range or reducing the page size of the area.

Additional Information

Description of deadlock message DC001000 

Additional deadlock details in message DC001001