Message-ID: <38A7BAA1.3BC1BC63@silcom.com> From: Lars Poulsen X-Mailer: Mozilla 4.61 [en] (Win98; I) X-Accept-Language: da,en MIME-Version: 1.0 Newsgroups: alt.folklore.computers Subject: OS/360 JCL: The DD statement and DCBs References: <20000211101241.23575.00002605@ng-fu1.aol.com> <38A756F5.C16E5FED@silcom.com> <38A7B3A9.249D3D7B@home.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 27 Date: Mon, 14 Feb 2000 00:19:45 -0800 NNTP-Posting-Host: 207.71.218.30 X-Complaints-To: abuse@avtel.com X-Trace: newsfeed.avtel.net 950515853 207.71.218.30 (Mon, 14 Feb 2000 00:10:53 PST) NNTP-Posting-Date: Mon, 14 Feb 2000 00:10:53 PST Organization: None X-Received-Date: Mon, 14 Feb 2000 00:10:53 PST (newsfeed.avtel.net) Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!news.maxwell.syr.edu!newsfeed.cwix.com!newsfeed.avtel.net!not-for-mail Xref: chonsp.franklin.ch alt.folklore.computers:49731 Lars Poulsen wrote: > > [...snip...] > > components called "access methods". The heart of JCL was the "DD" > > (data definition) statement, where the DCB (device control block) > > had fields available to override corresponding fields in a macro > > in the program. Pete Lamasney wrote: > Actually, you could not override something that was coded in the macro > in the program, but you could specify a value for something that was > omitted. Confession: I never wrote a line of ASMG in my life. (Although I read quite a bit; at one time I read the MVT SYSGEN manual in order to attempt to understand "how the system worked".) Some of the utility programs did some really bizarre things with their DCBs, including stuffing parameters they had read from their SYSIN DD's into the DCB before opening the file. But they still had to have a SYSUT1 DD card there, even if there was no information on it. Was the macro processor in JCL the same code as the macro processor in ASM, or was it a cut-and-paste job? -- / Lars Poulsen - http://www.cmc.com/lars - lars@cmc.com 125 South Ontare Road, Santa Barbara, CA 93105 - +1-805-569-5277 ###### From: jcmorris@jmorris-pc.MITRE.ORG (Joe Morris) Newsgroups: alt.folklore.computers Subject: Re: OS/360 JCL: The DD statement and DCBs Date: 14 Feb 2000 14:53:50 GMT Organization: The MITRE Corporation Lines: 62 Message-ID: <8894tu$peu$1@top.mitre.org> References: <20000211101241.23575.00002605@ng-fu1.aol.com> <38A756F5.C16E5FED@silcom.com> <38A7B3A9.249D3D7B@home.com> <38A7BAA1.3BC1BC63@silcom.com> Reply-To: jcmorris@linus.mitre.org NNTP-Posting-Host: jmorris-pc.mitre.org X-Trace: top.mitre.org 950540030 26078 128.29.251.13 (14 Feb 2000 14:53:50 GMT) X-Complaints-To: usenet@news.mitre.org NNTP-Posting-Date: 14 Feb 2000 14:53:50 GMT X-Newsreader: NN version 6.5.0 (NOV) Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!news.maxwell.syr.edu!newsfeed.icl.net!newspeer.clara.net!news.clara.net!news-lond.gip.net!news.gsl.net!gip.net!peer.news.th.u-net.net!u-net!tank.news.pipex.net!pipex!uunet!ams.uu.net!ffx.uu.net!news.tufts.edu!blanket.mitre.org!news.mitre.org!jmorris-pc.MITRE.ORG!jcmorris Xref: chonsp.franklin.ch alt.folklore.computers:49745 Lars Poulsen writes: >Confession: I never wrote a line of ASMG in my life. (Although I >read quite a bit; at one time I read the MVT SYSGEN manual in order >to attempt to understand "how the system worked".) A better way to figure it out was to read the SYSGEN macro source. Not only did this often provide commentary about what was being done, but often you could find hooks for goodies that were expected in the next release of the system. (And sometimes hooks for goodies that never made it out of development...) Nitpick: ASMG ("Assembler G") was a (very good) hack of the F-level assembler that IBM shipped with OS/360, but it came from Waterloo. It fixed many of the design limitations that were inherent in the ASM-F product -- showing once again why open source is a Good Thing for users. (OS/360 was not copyrighted, and shipped with source as a no-cost optional component.) >Some of the utility programs did some really bizarre things with >their DCBs, including stuffing parameters they had read from their >SYSIN DD's into the DCB before opening the file. But they still >had to have a SYSUT1 DD card there, even if there was no >information on it. The same programs required that the user provide a DD card pointing to each volume (but not to a specific data set on that volume) that would be used during the execution of the utility. This behavior was typical of the "system utility" programs such as IEHMOVE and IEHPROGM. In general, OS/360 required that each "data sets" (today's "files") to be used in an application (or utility) be identified by a unique DD card in the step's JCL prior to the start of execution. The system utilities played games with the system control blocks to avoid that requirement, but had to have a set of dummy control blocks that they could use to construct what amounted to pseudo-DD links on the fly. (When TSO was developed the OS/360 designers were finally forced to create an official "dynamic allocation" interface that obviated the need for much of this hacking.) One real advantage of the ability of the system utilities to work without individual DD cards for each data set was that you could work with huge numbers of data sets without requiring a correspondingly huge number of DD cards. And before someone jumps in to castigate IBM for not providing the ability to have programs run without JCL, please remember that the middle letter in "IBM" is B, for "Business". However restrictive the design is by today's standards, it grew out of -- and met -- the requirements of IBM's business customers at the time it was first designed -- in the early 1960s. >Was the macro processor in JCL the same code as the macro >processor in ASM, or was it a cut-and-paste job? Um...what "macro processor in JCL"? Beginning in OS/360 release 14 (released in 1969) you had the ability to do symbolic substitution of tokens (the syntax for which escapes me at this instant), and from 'way back when you had the ability to call a "cataloged procedure" -- is this what you are referring to? Joe Morris ###### Sender: lynn@LYNNPC Newsgroups: alt.folklore.computers Subject: Re: OS/360 JCL: The DD statement and DCBs References: <20000211101241.23575.00002605@ng-fu1.aol.com> <38A756F5.C16E5FED@silcom.com> <38A7B3A9.249D3D7B@home.com> <38A7BAA1.3BC1BC63@silcom.com> Reply-To: Anne & Lynn Wheeler From: Anne & Lynn Wheeler Message-ID: Organization: Wheeler&Wheeler Lines: 35 User-Agent: Gnus/5.0803 (Gnus v5.8.3) Emacs/20.5 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Mon, 14 Feb 2000 17:11:08 GMT NNTP-Posting-Host: 209.63.28.138 X-Complaints-To: support@adcomsys.net X-Trace: news-west.eli.net 950548268 209.63.28.138 (Mon, 14 Feb 2000 10:11:08 MST) NNTP-Posting-Date: Mon, 14 Feb 2000 10:11:08 MST Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!isdnet!netnews.com!newspeer1.nac.net!news.maxwell.syr.edu!cyclone1.usenetserver.com!cyclone1.usenetserver.com!easynews!news-west.eli.net!not-for-mail Xref: chonsp.franklin.ch alt.folklore.computers:49820 Lars Poulsen writes: > Some of the utility programs did some really bizarre things with > their DCBs, including stuffing parameters they had read from their > SYSIN DD's into the DCB before opening the file. But they still > had to have a SYSUT1 DD card there, even if there was no > information on it. asmg read jfcb (job file control block) macro could pull up the internal representation before the open. mostly i remember it being used by "monitors" ... i.e. programs that simulate stripped down job schedular for compile, load & go. Our shop converted 709 ibsys doing student fortran jobs measured in jobs per second (it was tape-to-tape, with 1401 acting as unit record front end) to OS/360 PCP 9.5 doing the same workload measured in minutes per job. adding hasp got it down to jobs per minute, but a 30 second 3-step fortran complie, lked, & go was still almost all job scheduler time. a monitor was tested that got it down to a couple seconds per student job ... but it was about the same time we installed watfor ... which got the 360/65 thruput on student fortran jobs back to finally better than the 709 ibsys random references: http://www.garlic.com/~lynn/93.html#1 http://www.garlic.com/~lynn/94.html#18 -- Anne & Lynn Wheeler | lynn@adcomsys.net, lynn@garlic.com http://www.garlic.com/~lynn/ http://www.adcomsys.net/lynn/ ###### Sender: lynn@LYNNPC Newsgroups: alt.folklore.computers Subject: Re: OS/360 JCL: The DD statement and DCBs References: <20000211101241.23575.00002605@ng-fu1.aol.com> <38A756F5.C16E5FED@silcom.com> <38A7B3A9.249D3D7B@home.com> <38A7BAA1.3BC1BC63@silcom.com> Reply-To: Anne & Lynn Wheeler From: Anne & Lynn Wheeler Message-ID: Organization: Wheeler&Wheeler Lines: 9 User-Agent: Gnus/5.0803 (Gnus v5.8.3) Emacs/20.5 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Mon, 14 Feb 2000 17:17:10 GMT NNTP-Posting-Host: 209.63.28.138 X-Complaints-To: support@adcomsys.net X-Trace: news-west.eli.net 950548630 209.63.28.138 (Mon, 14 Feb 2000 10:17:10 MST) NNTP-Posting-Date: Mon, 14 Feb 2000 10:17:10 MST Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news-ge.switch.ch!newscore.univie.ac.at!194.25.134.126.MISMATCH!newsfeed01.sul.t-online.de!t-online.de!newsfeed.tli.de!remarQ-easT!remarQ.com!supernews.com!cyclone1.usenetserver.com!cyclone1.usenetserver.com!easynews!news-west.eli.net!not-for-mail Xref: chonsp.franklin.ch alt.folklore.computers:49813 also, another interesting reference: http://jmaynard.home.texas.net/hercos360/ -- Anne & Lynn Wheeler | lynn@adcomsys.net, lynn@garlic.com http://www.garlic.com/~lynn/ http://www.adcomsys.net/lynn/