What is DUMMY dataset

krbabu · New User Joined: 20 Feb 2004 Posts: 57

hi all,

Can anybody explain about what is DUMMY data set and what is its use?

sandip_datta · Posted: Thu Feb 26, 2004 3:27 pm

Hello Ravindra,

Dummy dataset is a welknown concept in CA-7.

Say there are partner systems from where you receive files and you want that when one particular file is reached in your system a particular job say JOB1 at your end will be triggered. In this case the partner system should send a dummy dataset A.JOB1 to your system after the original file and in your side JOB1 will have a dependency in that dummy dataset. This can be done in CA-7. When the dummy dataset reaches in your system the job will automatically started.

You can also check in CA-7 whether the dummy dataset has reached or not.
LCTLG,DSN=A.JOB1,LIST=ALL

I think others can give you a very good language from manual. Let's wait for that.

Regards,
Sandip.

Johore · Specialist Joined: 12 Sep 2003 Posts: 19

Are you asking about the DD DUMMY we use in JCL

If so then Dummy is used instead of DSN=dataset name to run the job for testing purposes , when we dont have actual data or the dataset with us. The Job will not abend with DATASET NOT FOUND.

pr_ibm · New User Joined: 04 May 2005 Posts: 9

Yes you are correct Johor. If you dont know the file or some times there is a requirement like we dont want all the files in the job then if we omit any DD name we will get abend. So to avoid this situation we use DUMMY.

Thanks
PR...

gnagakishore · New User Joined: 26 Mar 2005 Posts: 25 Location: Hyderabad

dummy parameter is used to test the execution of the program with out
being reading or writing into it.

mmwife · Super Moderator Joined: 30 May 2003 Posts: 1592

This is to correct the misconception that DD DUMMY is only used in a test environment. It is used quite often in production situations where a given run of a pgm doesn't require ALL the O/Ps generated by the pgm.

To generate them wastes DA space and can also confuse the collection of generations in a GDG.

vivek_mvs1 · New User Joined: 25 Apr 2006 Posts: 12

Hi,

Dummy is used one of my application. It is used to Deload a dataset throuh IDCAMS utility

skkp2006 · Posted: Tue Jul 18, 2006 11:43 am

Dummy dataset can be used in multiple scenarios.But what DD Dummy actually does is that it ignores the input and the output parameters(like disp,space,vol).Correct me if i am wrong

shreevamsi · Posted: Tue Jul 18, 2006 2:04 pm

Hi,

DUMMY...some times usefull in case of Generic Programs.

The DD is Coded with a Dataset/Dummy based on the requirement.

For Example, a program generates a Monthly Report and Daily Reports.

When Monthly Job is Run, The dataset to create Daily Report is Coded as Dummy.
Similarly, for daily job, monthly report dataset is DUMMY.

note: In both the scenarios, the PGM is same, creating Daily and Monthly Reports.

But the Job output varies from the Run.

~Vamsi

parikshit123 · Active User Joined: 01 Jul 2005 Posts: 269 Location: India

Holger · New User Joined: 24 Oct 2006 Posts: 2

Hi all,

DUMMY has in above the same meaning as NULLFILE and is used to suppress unused files. If you use it, it handles files as non existing.

You can use it for example in IDCAMS with various input and output files.
You have 20 input and 20 output files, but you only want to use the 9th thru 13th input/output files without changing the sysin instructions (REPRO).
So you set inpu/output file 1 thru 8 and 14 thru 20 to DD DUMMY.
It works, try it.

If you use it in a concatenated DD statement, be careful, because it
identifies the EOF in the DD DUMMY, so it is the best way to place it
at the end of a DD instruction.

All parameters used after a DD DUMMY, are ignored, this is the difference between NULLFILE and DD DUMMY. NULLFILE recognizes applied parameters.

Greetings
Holger

Holger · New User Joined: 24 Oct 2006 Posts: 2

One additional information. If you want to create an eighty bytes lon dataset, you can use DUMMY as input file with DCB=LRECL=80 and create an output file from this file is created with this attributes.

Greetings
Holger