Even without modifying the SWA with information for the DD, as you suggested earlier?
On Tue, Apr 21, 2015 at 2:50 PM, John McKown <[email protected]> wrote: > On Tue, Apr 21, 2015 at 3:00 AM, Steff Gladstone < > [email protected]> > wrote: > > > Thank you all for for help. The obvious question that remains is: how > > does the operating systen itself maintain a continuous ENQ over several > job > > steps for a dataset allocated in the first step with disp=(mod,pass)? Is > > there a special privileged ENQ operation that only the operating system > has > > access to? > > > > > No, there is not a special ENQ. The initiator TCB, which exists for as > long as the initiator is running, issues the ENQ. > > The initiator (in general terms) is what reads the parsed JCL and creates > the SWA control blocks which represent the job. This code then knows the > DSNs in the job and issues a single ENQ for _all_ of them before starting > the first step. As each step ends, the initiator does a DEQ on the DSNs > which are not going to be used in subsequent steps. At the end of the job, > it DEQs whatever DSNs are left. > > This means that you _could_ use a directed ENQ to put the DSN on the ENQ > chain for the initiator TCB, as you mentioned in a previous post. But since > the initiator does not know anything about that, it will not know to do a > DEQ to release it at end of job. This is why you would need a terminating > step to do the DEQ. Thinking about it a bit more, given what Mr. Relson > said about RTM, doing this _should_ work even if the initiator terminates > abnormally since RTM should clean up the ENQs during EOM processing. > > > -- > If you sent twitter messages while exploring, are you on a textpedition? > > He's about as useful as a wax frying pan. > > 10 to the 12th power microphones = 1 Megaphone > > Maranatha! <>< > John McKown > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
