-----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. In the MVS world, DCB is DCB -- We don't have DCBSD for Data Control Block - Sequential Disk. The Access Method connects you to the device and handles it (unless you went out of your way to make the DCB specific to a device, such as a card reader). As you can see, there is device dependence and then there is device dependence. Regards, Steve Thompson -- Opinions expressed by this poster may not reflect those of poster's employer. -- ---------------------------------------------------------------------- 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
