the use of AVGREC parameter.

mf_user · New User Joined: 05 Jan 2006 Posts: 47

Hi,

I have created a new OUTPUT dataset in the following way:

//SYSUT1 DD DSN=INPUT.DATASET.IP,
// DISP=(NEW,CATLG,CATLG),
// SPACE=(1048,(10,5),RLSE),
// VOL=(,,,5),
// UNIT=PERMDA,
// AVGREC=K,
// RECFM=FB,
// LRECL=1048,
// BLKSIZE=27248
//*

Due to huge incoming data the job abended with SB37. So, the programmer did the following change and reran the job successfully.

//SYSUT1 DD DSN=INPUT.DATASET.IP,
// DISP=(NEW,CATLG,CATLG),
// SPACE=(1500,(10,5),RLSE),
// VOL=(,,,5),
// UNIT=PERMDA,
// AVGREC=K,
// RECFM=FB,
// LRECL=1048,
// BLKSIZE=27248
//*

After completion of the job, the dataset was created with the LRECL of 1048 only. I would like to know how it could be possible even though the SPACE param was changed to have a AVGREC of 1500. (1048 value was changed to 1500 !!!!)

Your inputs are most welcome to make this understand.

Thanks 4 ur time.

Gautam512 · Posted: Fri Jan 13, 2006 12:30 pm

HI,

Space parameters are no way related to the LRECL.

SPACE parameter requests space for a new data set on a DASD
volume. You can either request an amount of space and let MVS
locate the space for you, or you can request specific track numbers
on a DASD volume.

The LRECL parameter is used to specify the logical record length for the records in a data set. Its function is equivalent to that of the LRECL= subparameter of the DCB=parameter.
LRECL can be used to override the LRECL information for a data class
if SMS (System Managed Storage) is installed and active.

Thanks,
Gau

gowtham_1982 · Active User Joined: 02 Dec 2005 Posts: 109

mf_user · New User Joined: 05 Jan 2006 Posts: 47

So, instead of giving the

SPACE=(LRECL,(M,N),RLSE),
AVGREC=K,
LRECL=250

I can also give as mentioned here

SPACE=(TRKS,(M,N),RLSE),
AVGREC=K,
LRECL=250

Please enlighten me.

Gautam512 · Posted: Fri Jan 13, 2006 8:08 pm

Hi mf_user,

Go thru the attachemetn ,u'll have gud idea of space parameter.....

Thanks,
Gau

mf_user · New User Joined: 05 Jan 2006 Posts: 47

Thanks for the doco.

Gautam512 · Posted: Tue Jan 17, 2006 6:24 pm

Ur most welcome .........

Thanks,
Gau

priya · Posted: Sat Feb 16, 2008 3:25 am

leo_sangha · New User Joined: 11 Aug 2005 Posts: 85 Location: England

expat · Posted: Wed Apr 02, 2008 7:47 pm

Well, however you decide to allocate your DASD space, the operating system always converts in into either tracks or cylinders, which are the only two values accepable by the DASD subsystems.

It's not difficult to work out space requirements, so why not just stick to TRK & CYL

leo_sangha · New User Joined: 11 Aug 2005 Posts: 85 Location: England

Thanks for the prompt reply.

But still i would like to know what will happen if i code the space parameters like :

I know that if i code:
LRECL=100,
SPACE=(100,(50,10),RLSE),AVGREC=K

MVS will allocate space equivalent to (50 X 1024 records) of LRECL 100.

what will happen if i code

LRECL=100,
SPACE=(CYL,(50,10),RLSE),AVGREC=K

how will MVS allocate space ? Thanks !

enrico-sorichetti · Posted: Wed Apr 02, 2008 11:47 pm

The manual is clear

leo_sangha · New User Joined: 11 Aug 2005 Posts: 85 Location: England

Thanks Enrico, it was really helpful.

I am left to assume in production either SMS is not installed or NOT active, otherwise the job should have abended(Reason - Syntax Error), for coding space parameters as below :

SPACE=(CYL,(50,10),RLSE),AVGREC=K

And the AVGREC parameter is getting ignored all the times.

Am i on the right track now

enrico-sorichetti · Posted: Thu Apr 03, 2008 7:02 pm

almost

as the docs says avgrec is ignored when the allocation unit does not represent a record length ( not numeric )

vamskrish · New User Joined: 31 Jan 2007 Posts: 27 Location: virginia

AVGREC=U - means 100's of records
AVGREC=K - means 1000's of records
AVGREC=M - means millions of records

when u use AVGREC parameter, u dont use CYL OR TRKS in ur space parm. instead u use the record length of the file.

for ex:

SPACE=(100,(10,5),RLSE),AVGREC=K means that ur output file can handle
primary space for 10 * 1000 = 10,000 records each of length 100. this is the best practice to avoid using CYL and TRKS.

similarly
SPACE=(100,(10,5),RLSE),AVGREC=M, means ur output file can handle 10 million records.

if u know approx., how many records ur output file will have then u can use AVGREC. if there are million records and if u have mentioned
AVGREC = K, then u will get space abend.