> This is just a curious question about how the JCL DD SUBSYS paramater works. > With BLSR you allocate a file to use BLSR with something like this: > > //INETACC DD SUBSYS=(BLSR,'DDNAME=INETACC@ MSG=I', > // 'RMODE31=ALL BUFND=256 BUFNI=64 DEFERW=YES') > //INETACC@ DD DSN=&DSNENV..INET.INETACC, > // DISP=SHR > > Is there a specific reason why its not the more obvious (to me!) waylike this? > > //INETACC DD DSN=&DSNENV..INET.INETACC,DISP=SHR, > // SUBSYS=(BLSR,'MSG=IRMODE31=ALL BUFND=256 BUFNI=64 DEFERW=YES')
BLSR was originally written at Washington Systems Center as an assembler language subsystem, which was going to be included with the book "The Subsystem Interface in MVS/SP Version 3 GC66-3131-00 August 1989" as a sample program, and named PHPD after the authors (Penny Heming, Paul Dorn). That was done without the involvement of MVS or DFP development, so there was no opportunity to modify operating system code. That code ended up being rewritten in PL/AS, renamed as Batch LSR, and shipped as a PTF on top of MVS SP 3.1.3. With the syntax, you are proposing, an OPEN for INETACC would be treated as a subsystem OPEN, and control would be routed to the BLSR subsystem. But there would be no DDNAME for which BLSR could subsequently do a VSAM OPEN. Now, maybe it would have been possible for BLSR to retrieve the necessary information and do a dynamic allocation to create its own DDNAME for the VSAM data set. I don't know if the original PHPD authors ever considered that possibility. It would have been considerably more complex, and probably beyond the scope of what they were trying to accomplish. Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
