What if a new device came out and there was a better optimum blocksize for it? Wouldn't you have to recompile everthing that used that file to get the optimum blocksize? I don't know I'm just asking.
-----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Gilbert Saint-Flour Sent: Friday, May 15, 2009 8:29 AM To: [email protected] Subject: Re: BLOCK CONTAINS On Friday 15 May 2009 02:05, Frank Swarbrick wrote: > We are migrating from VSE to z/OS, and at the same time we are going > to convert most of our existing ESDS files to regular sequential files. > I see no reason to add "BLOCK CONTAINS 0" to all of our FD's if it has > no affect (our VSAM FD's do not (generally!) specify the BLOCK CONTAINS > clause, because it has no meaning to VSAM). IIRC, BLOCK CONTAINS 0 is only needed for OUTPUT files in COBOL, but I think it's better to put it everywhere, so programmers later don't have to remember where it's needed. In 1991, I started to convert VSE applications to MVS/ESA and stopped to generate DCB attributes on DD statements, except for output files in IDCAMS REPRO and QUIKJOB programs, and a few others ones. A few years later, I started to convert IDCAMS REPRO to something else, for several advantages, among them not having to specify DCB info in the JCL. I'm convinced that coding DCB attributes on DD statements is something almost always useless and archaic. This is something all my customers agreed with, except an outsourcing company that absolutely had to have DCB information on all output DD statements, like this: DCB=(RECFM=xx,LRECL=yy,BLKSIZE=zzz). This was in 2007 ! In z/OS ! See examples here: http://gsf-soft.com/Prism-CS/Samples.shtml and you won't see many DD statements that contain DCB info. This is very similar to what I generated since 1991. As for the conversion of ESDS files to non-VSAM in COBOL programs, changing AS-filename to S-ddname is not always the only thing you need to do. Trust me ! -- Gilbert Saint-Flour GSF Software http://gsf-soft.com/ ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ========================== This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to which they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
