On 5/09/2018 5:31 AM, Gord Tomlin wrote:
This thread started off with a discussion regarding the use of
ISPF-style SPFEDIT ENQs for serialization. While those ENQs protect
against simultaneous updates by multiple ISPF users, they do not
protect against updates by other non-ISPF programs, such as IEBCOPY,
IEBGENER, or many others.
Using SPFEDIT ENQs in Zowe would have the same strengths and
weaknesses as using those ENQs in ISPF.
An ENQ convention can only truly be relied upon if all users of the
system follow that convention. SPFEDIT falls short in that.
ISPF also does a SYSDSN ENQ on the dataset.
IEBCOPY, IEBGENER etc. do not do ENQs - you write the JCL to do the ENQ.
If you are updating a dataset you are supposed to use DISP=OLD, which
will protect you against concurrent updates, including ISPF edit. Many
use DISP=SHR because it is more convenient, but then it is your decision
to give up the protection of DISP=OLD - whether it is from ISPF, or
other instances of IEBCOPY, IEBGENER etc.
There are many examples where updates using DISP=SHR can cause problems
including data loss. If the customer chooses to do that they own the
problem.
Is there any IBM software that handles its own ENQs (as opposed to
relying on what the customer codes in JCL) that is not compatible with
ISPF and it's use of SYSDSN and SPFEDIT? My gut feeling is that if there
was it would be APARable, but I don't know.
--
Andrew Rowley
Black Hill Software
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