VSE Lock file

[Ernie J. Carney]

When running several z/VSE 5.2 guests sharing disks, does the system lock a Disk device using device address or volume name, or both?

 

 

Thanks in advance

 

E J Carney

DOB Systems, LLC

[Mick Poil]

Ernie,

Only the whole Lock File cuu is locked against concurrent update at the volume level as I remember using (Virtual) Reserve/Release. VSE uses LOCK/UNLOCK/DTL macros to lock at the VSAM dataset/library level in most cases, but not all of them as there are many possibilities. VSAM uses the volser of the volume that has the catalog to lock a cluster.

Why the question?

Mike

[Mick Poil]

They are described in a number of DRMs, some of which you might only find if you look at the VSE/ESA V2 DRM list and even then you might not get them all.

Resource names cannot be be bigger than 12 bytes. As I remember, the facility appeared about 1980 when storage was at a premium and the Lock table size was defined in the Supervisor generation and was limited in size. I recall looking at a lot of  stand-alone dumps for one customer, logging many calls at the Support Centre and then finding out a short while afterwards that it was all fixed by PUT 8012. This accounts for obscure conventions whereby a VSAM cluster lock is based on the volser of the VSAM catalog concatenated with the CI number in the high-key range that defines the cluster entry.

This reminds me that I am getting old (I get my free bus pass next January!).

Mike