what is use of SYSIN DD DUMMY

krishna_mf · New User Joined: 31 Jan 2007 Posts: 56 Location: banglore

hi
can anyone please tell me what is practical use of
sysin dd dummy

why do we use dummy dataset.

sandeep1dimri · New User Joined: 30 Oct 2006 Posts: 76

To simulate the file environment for the program which writes/read the files
so instead of providing the file we put a Duumy in the same fashion that we are provinding an empty file

vinay upadhyay · New User Joined: 13 May 2007 Posts: 14 Location: chennai

The dummy parameter is coded in DD statement to test the execution of a program without actually reading or writing a dataset. The OS actully simulates the presence of dataset.

dick scherrer · Posted: Sat May 19, 2007 7:29 pm

Hello,

If you specify DD DUMMY and read the file, it will raise the "at end" on the first read. If you write to a DD DUMMY, it does no/io, but the program runs as thought it was creating output. This can be handy if you need to run a program that has several outputs and you only need part of them - especially if an output is a very large report that is not needed for this particular run.

DD DUMMY is often used as a "place-holder" for clarification that there is as dataset used there and is overridden at execution with the actual DD information for the run.