On Fri, 15 May 2009 10:34:31 -0400, Thompson, Steve <[email protected]> wrote:
>-----Original Message----- >From: IBM Mainframe Discussion List [mailto:[email protected]] On >Behalf Of Paul Gilmartin >Sent: Friday, May 15, 2009 9:07 AM >To: [email protected] >Subject: Re: BLOCK CONTAINS > >On Fri, 15 May 2009 09:27:42 -0400, Thompson, Steve wrote: >> >>Welcome to the MVS world. In the MVS world, we are not device >dependant, >>nor are we data definition locked/blocked. We generally don't have to >>recompile our programs, change the DTF contents (DCB in MVS), etc. just >>because the file attributes change (xSAM to VSAM is the exception). >> >Huh??? > >If "we are not device dependant", why is there such intense trepidation >and resistance to the mere suggestion of a device with a novel geometry >such as more bytes per track or more tracks per cylinder? It doesn't >appear that you and I have been living in the same MVS world. > ><SNIP> > >In the VSE world, if you set up to read tape, you can not change your >JCL to instead read Disk. A DTFSD (Define The File - Sequential Disk) >can not be used to read a tape (DTFMT - Define The File - Magnetic >Tape). > >If you did use the DTFDI (Define The File - Device Independent) it is >only good for limited situations. I don't know what assembler stuff is done under the covers, but in Cobol for VSE/ESA (and VS COBOL II) you can use a single SELECT statement that will work with printers, tape files, sequential files and VSAM-managed SAM files. SELECT MY-FILE ASSIGN TO SYS005-MYFILE. Frank ---------------------------------------------------------------------- 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
