On 19/04/2012 10:50 PM, Michael Klaeschen wrote:
I do not agree to Paul's answer. flockfile() only relates to file
descriptors. Opening another file descriptor for the same file will not be
in scope of that particular lock. Instead you might consider BPX1FCT with
the BPXYBRLK mapping structure. However, as found in the "important note"
of v_lockctl description in PFS File System Interface Reference, all
locking mechanisms are just convention for well-behaving processes and do
not guarantee exclusive use.
BPX1FCT = fcntl() right?
IMHO, POSIX and common Unix implementations just don't offer exclusive
control as found in MVS (i.e. GRS). May be you can use ISGENQ to obtain an
enqueue for Unix resources -- but beware of being overconfident.
Of course, fcntl() can be used to implement byte-range-locking. So in
theory you could use it to implement
row-level locking in a dictionary library. ENQ is not that granular.
Cheers
Michael
Von: Elardus Engelbrecht<elardus.engelbre...@sita.co.za>
An: IBM-MAIN@bama.ua.edu
Datum: 2012-04-19 16:13
Betreff: Re: USS File Integrity
Gesendet von: IBM Mainframe Discussion List<IBM-MAIN@bama.ua.edu>
Donald Likens wrote:
I just ran two STCs that updated the same z/OS USS file at the same time.
How do I stop multiple processes from updating the same z/OS USS file at
the same time?
Paul gave you a very good answer, but I wonder how was that USS file
allocated in the first place? Dynamic Alloc, JCL DD statement, other
method perhaps?
Does it (allocation method) matters despite usage of flockfile()?
Just curious of course.
zMan: I think your father WWII ship is still sailing somewhere ( near that
lovesick whale? :-D ) because of the constant disagreement about *true
unfathomable* meaning of USS!!! :-D
Groete / Greetings
Elardus Engelbrecht
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