When did this become available 
Author Message
 When did this become available

I was reading some JCL the other day and it went something like this:

//MYFILE  DD  DISP=SHR,DSN=MY.FILE,BLKSIZE=8000

So I tried it, and it worked.  When did BLKSIZE become a valid DD parameter and
not just a sub-parameter of DCB? - e.g. DCB=(BLKSIZE=8000) or DCB=BLKSIZE=8000?
 Is this an OS/390 feature? Is this a DFSMS feature?



Thu, 12 Jul 2001 03:00:00 GMT  
 When did this become available
That feature has been around for quite awhile now.  All of the DCB subparameters
can be entered this way, including LRECL, BUFO, RECFM, etc.  I don't think that
this is SMS related.

Also added about this time was the ability to create a VSAM file without using
IDCAMS, e.g.:

//MYFILE DD DSN=MY.FILE,RECORG=KS,KEYLEN=10,KEYOFF=0

This would define a KSDS, key length of 10, relative key position (RKP) of 0.  This
can only be done if SMS is installed. Perhaps this common knowledge, but I think
it's pretty cool.

See also:

Title: OS/390 V1R1.0 MVS JCL User's Guide
Document Number: GC28-1758-00

and

Title: OS/390 V1R1.0 MVS JCL Reference
Document Number: GC28-1757-00

Both can be found online at:

http://ppdbooks.pok.ibm.com:80/cgi-bin/bookmgr/bookmgr.cmd/library

I hope this helps.

Regards,

John Parke

Quote:

> I was reading some JCL the other day and it went something like this:

> //MYFILE  DD  DISP=SHR,DSN=MY.FILE,BLKSIZE=8000

> So I tried it, and it worked.  When did BLKSIZE become a valid DD parameter and
> not just a sub-parameter of DCB? - e.g. DCB=(BLKSIZE=8000) or DCB=BLKSIZE=8000?
>  Is this an OS/390 feature? Is this a DFSMS feature?



Thu, 12 Jul 2001 03:00:00 GMT  
 When did this become available
 >
 > That feature has been around for quite awhile now.  All of the DCB
subparameters
 > can be entered this way, including LRECL, BUFO, RECFM, etc.  I don't
think that
 > this is SMS related.
 >
 > Also added about this time was the ability to create a VSAM file
without using
 > IDCAMS, e.g.:
 >
 > //MYFILE DD DSN=MY.FILE,RECORG=KS,KEYLEN=10,KEYOFF=0
 >
 > This would define a KSDS, key length of 10, relative key position
(RKP) of 0.  This
 > can only be done if SMS is installed. Perhaps this common knowledge,
but I think
 > it's pretty cool.
 >
 > See also:
 >
 > Title: OS/390 V1R1.0 MVS JCL User's Guide
 > Document Number: GC28-1758-00
 >
 > and
 >
 > Title: OS/390 V1R1.0 MVS JCL Reference
 > Document Number: GC28-1757-00
 >
 > Both can be found online at:
 >
 > http://ppdbooks.pok.ibm.com:80/cgi-bin/bookmgr/bookmgr.cmd/library
 >
 > I hope this helps.
 >
 > Regards,
 >
 > John Parke
 >
 >
 > > I was reading some JCL the other day and it went something like
this:
 > >
 > > //MYFILE  DD  DISP=SHR,DSN=MY.FILE,BLKSIZE=8000
 > >
 > > So I tried it, and it worked.  When did BLKSIZE become a valid DD
parameter and
 > > not just a sub-parameter of DCB? - e.g. DCB=(BLKSIZE=8000) or
DCB=BLKSIZE=8000?
 > >  Is this an OS/390 feature? Is this a DFSMS feature?  

The same is true for the LABEL subparameters; EXPDT= & RETPD=.

================================

================================



Thu, 12 Jul 2001 03:00:00 GMT  
 When did this become available

Quote:
> I was reading some JCL the other day and it went something like this:

> //MYFILE  DD  DISP=SHR,DSN=MY.FILE,BLKSIZE=8000

Regardless of the above, I now always use BLKSIZE=0 and let the system
assign the most optimum blocksize for whatever device my file is going
to.  They're constantly rotating our disk drives around so a factor
for one type won't be as efficient on another, and sometimes we go
to cart or tape.


Fri, 13 Jul 2001 03:00:00 GMT  
 When did this become available

Quote:

>Anyway, if you dont specifiy BLKSIZE=0 you will get a system system
>calculated BLKSIZE (unless you have mean systems programmers), so why put
it
>in?

In our shop we omit all blksize parms, and let the system decide. Problem we
have is that if a file is empty (created by job but nothing written to it),
the blocksize for the file is 0, and this makes certain utils (e.g. "UGET"
file transfer utils to the PC) complain, and that make our dumb users
complain. Might be just our site that need to look at some of these utils

Leon



Sat, 14 Jul 2001 03:00:00 GMT  
 When did this become available
 >
 > >
 > >Anyway, if you dont specifiy BLKSIZE=0 you will get a system system
 > >calculated BLKSIZE (unless you have mean systems programmers), so
why put
 > it
 > >in?
 > >
 >
 > In our shop we omit all blksize parms, and let the system decide.
Problem we
 > have is that if a file is empty (created by job but nothing written
to it),
 > the blocksize for the file is 0, and this makes certain utils (e.g.
"UGET"
 > file transfer utils to the PC) complain, and that make our dumb users
 > complain. Might be just our site that need to look at some of these
utils
 >
 > Leon

In this case the file was never accessed in the program and the "file"
is really nothing more than a name in the catalog and vtoc, placed there
by JCL processing alone.  This has always been the case.  I make it a
rule of thumb to open and close each file even if nothing is ever
written to it.  This will prevent the blksize 0 problem and prevent
subsequent utilities (and others) from blowing up.

================================

================================



Sat, 14 Jul 2001 03:00:00 GMT  
 
 [ 8 post ] 

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