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Posted by: Bob Cozzi
Rogue Programmer
Cozzi Productions, Inc.
Chicagoland
Any downside to turning off QLIBLCKLVL?
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Published: 16 Feb 2012
Revised: 23 Jan 2013 - 1580 days ago
Last viewed on: 21 May 2017 (2982 views) 

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Any downside to turning off QLIBLCKLVL? Published by: Bob Cozzi on 16 Feb 2012 view comments(1)

I'm considering changing the System Value QLIBLCKLVL from the shipped default of '1' (on) to '0' (off). This would avoid having jobs that contain a library on their library list from locking those libraries from other functions, such as save/restore, clear, delete, rename, etc.

Has anyone ever worked with this system value before?

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Posted by: DaleB
Premium member *
Reading, PA
Comment on: Any downside to turning off QLIBLCKLVL?
Posted: 5 years 3 months 5 days 19 hours 21 minutes ago

No, but found a Redpaper authored by Dawn May and others. They recommend '0'. Apparently system jobs, subsystem monitors, and secondary threads do not lock the library list anyway. It's only a regular job's primary thread that locks. It mentioned a performance benefit by reducing number of locks on the system.

Don't know what happens to an active job if you delete or rename a library that's in it's library list. Guessing it will probably would be OK until next time it tries to find an unqualified object, then it will end abnormally. (Not entirely unlike *PGM in a call stack, DLTPGM, then calls eventually return to the non-existent program.)

Before I clear, delete, or rename, I do WRKOBJLCK on *LIB; you'll lose that. To be safe you'd need a little program or command that lists all jobs and checks their library lists.

Save won't be affected, really. You'll still need save-while-active because of objects in the library.