IBM Mainframe Forum Index
 
Log In
 
IBM Mainframe Forum Index Mainframe: Search IBM Mainframe Forum: FAQ Register
 

Difference bw NULLFILE & DUMMY


IBM Mainframe Forums -> JCL & VSAM
Post new topic   This topic is locked: you cannot edit posts or make replies.
View previous topic :: View next topic  
Author Message
subhasis_50

Moderator


Joined: 09 Mar 2005
Posts: 363
Location: Earth

PostPosted: Thu May 26, 2005 9:50 am
Reply with quote

Hi,
What is the difference between
DD DUMMY
and
DD DSN=NULLFILE
Back to top
View user's profile Send private message
vishal_a

New User


Joined: 24 May 2005
Posts: 45
Location: Noida

PostPosted: Thu May 26, 2005 11:50 am
Reply with quote

icon_cool.gif hi Subhasis
well actually there is no difference b/w both
we can use sysin dd dummy or nullfile will work as same
no i/o function will be done on dataset
regards
vishal
Back to top
View user's profile Send private message
kanak

Moderator


Joined: 12 Mar 2005
Posts: 252
Location: India

PostPosted: Thu May 26, 2005 12:01 pm
Reply with quote

I agree with vishal.There is no difference.
The system bypasses all input/output operations, does not
allocate devices or storage to the data set, and does not perform disposition processing.
Back to top
View user's profile Send private message
avalanches

New User


Joined: 10 May 2005
Posts: 28

PostPosted: Thu May 26, 2005 12:43 pm
Reply with quote

Hi,

Does it make any difference in using DUMMY or NULLFILE in the copying? Say initializing an empty file. I've used copying NULLFILE. What about DUMMY?

avalanches
Back to top
View user's profile Send private message
SteveConway

New User


Joined: 26 May 2005
Posts: 28
Location: Northern VA, USA

PostPosted: Thu May 26, 2005 6:45 pm
Reply with quote

The previous posters are correct, there is no difference in the processing of DD DUMMY and DD DSN=NULLFILE. There are documented restrictions on the use of NULLFILE, primarily no use as a temp file dsn or a pds name with member specified.
DSN=NULLFILE works as a nice placeholder in a proc for a file that is used intermittently, or has a varying dataset name. You can code all other attributes (DCB, UNIT, SPACE, etc.) and then just override the DSN if you need it. Of course, you can do the same with DD DUMMY; DSN=NULLFILE just lines up neater. :-)
Back to top
View user's profile Send private message
xstortion

New User


Joined: 27 May 2005
Posts: 4
Location: NJ, USA

PostPosted: Fri May 27, 2005 7:30 pm
Reply with quote

SteveConway wrote:
The previous posters are correct, there is no difference in the processing of DD DUMMY and DD DSN=NULLFILE. There are documented restrictions on the use of NULLFILE, primarily no use as a temp file dsn or a pds name with member specified.
DSN=NULLFILE works as a nice placeholder in a proc for a file that is used intermittently, or has a varying dataset name. You can code all other attributes (DCB, UNIT, SPACE, etc.) and then just override the DSN if you need it. Of course, you can do the same with DD DUMMY; DSN=NULLFILE just lines up neater. :-)


Great answer cosmetic reasons we are so vane icon_lol.gif
Back to top
View user's profile Send private message
enrico-sorichetti

Senior Moderator


Joined: 14 Mar 2007
Posts: 10727
Location: italy

PostPosted: Mon Oct 17, 2016 4:33 pm
Reply with quote

Topic cleaned up,

posted a sticky on the same subject
Back to top
View user's profile Send private message
View previous topic :: :: View next topic  
Post new topic   This topic is locked: you cannot edit posts or make replies. View Bookmarks
All times are GMT + 6 Hours
Forum Index -> JCL & VSAM

 


Similar Topics
Topic Forum Replies
No new posts Difference between CEE3250C and CEE3204S COBOL Programming 2
No new posts Difference between sysexec and sysproc CLIST & REXX 6
No new posts Difference between DATACLAS=MULTIVOL ... JCL & VSAM 10
No new posts Difference between CICS region bounce... CICS 3
No new posts Difference between GE and GB return c... IMS DB/DC 8
Search our Forums:

Back to Top