DCB parameters MLDSCB

anuradha · Posted: Wed Jan 07, 2004 5:20 pm

HI

,

I HAD A DOUBT IN DCB PARAMETERS.I HAD ONLY SOME 3 MONTHS OF EXPERIENCE IN MAINFRAMES.IN MY COMPANY THEY WILL CODE AS:

//SYSUT3 DD DSN=MISS.P.HMAAT.BAL.COUNT(0),
// DISP=(MOD,KEEP,KEEP),
// UNIT=SYSDA,SPACE=(10796,(800,300),RLSE),
// DCB=(MLDSCB,DSORG=PS,RECFM=FB,
// LRECL=100,BLKSIZE=0)

IN THE ABOVE CODE IN DCB PARAMETERS WHAT IS THAT MLDSCB.EVEN OUR COMPANY PPL DONT KNOW THAT CLEARLY.CAN ANYONE PLEASE CLARIFY MY DOUBT.

THANKS AND REGARDS
ANURADHA

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

Hi ANURADHA,

GDG datasets require a model DSCB (don't think it's required if the GDG is SMF managed).

A model DSCB is a cataloged disk dataset (usually created w/no DCB info and zero SPACE to permit use by any newly created GDG dataset).

When GDG datasets are created the model DSCB must be specified and the DCB info for that dataset specified as overides to the DCB info of the model DSCB.

Regards, Jack.

anuradha · Posted: Thu Jan 08, 2004 11:02 am

HI JACK,

THANKS A LOT JACK.BUT FROM YOUR ANSWERS STILL SOME MORE DOUBTS RAISED.

1.CAN'T WE CREATE A GDG WITHOUT A MDL DSCB.ANYWAY WE ARE OVERRIDING IT.THEN Y IT IS REQUIRED?
2.UPTO NOW I HEARD LIKE SMS(STORAGE MANAGEMET SUBSYSTEM).WHAT IS THIS SMF.DOES SMF STANDS FOR STORAGE MANAGEMENT FACILITY.WHEN IAM LEARNING OUR MAINFRAME SYSTEM IS SMS MANAGED.THERE WE CREATED GDG'S WITH MODEL GDG WHERE THAT MODEL GDG'S DCB PARAMETERS CAN BE APPLIED FOR THE NEW ONE .
3.LAST BUT NOT LEAST,WITHIN SOME SHORT DURATION I WANT TO BECOME AN EXPERT LIKE YOU IN MAINFRAMES.WHAT TIPS I CAN FOLLOW FOR THAT.I WANT TO DEDICATE MY LIFE TOTALLY FOR THIS FIELD.PLZZ HELP ME.

THANKS A LOT FOR ANSWERING ALL MY QUESTIONS WITH PATIENCE.THEY MAY APPEAR AS SILLY QUESTIONS FOR YOU.BUT IAM ASKING ALL THIS OUT OF MY CURIOSITY.

THANKS AND REGARDS
ANURADHA

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

Hi ANURADHA,

There's an old saying: "The only silly questions are those that are not asked".

You're right, I meant to say SMS not SMF. SMF is System Mgmt Facility. a facility that records various system activities in SMF Log datasets.

Why we must code a model DSCB? I don't know. I guess somebody at IBM thought it was a good idea at the time.

How do you become an expert? Someone said: "Make more mistakes than anyone else."

There's some wisdom in that thought. The big thing is to keep on keeping on. Read the manuals instead of that new novel.

Also read the books too. The manuals do a good job of telling you HOW, but are weak when it comes to WHY. An example: for years I've read in the IDCAMS manual about IN/OUTFILE and IN/OUTDATASET and I knew how to code the stmts but I didn't know why you'de use one instead of the other. It took me years to find out.

Good luck and keep on keeping on, Jack.

anuradha · Posted: Fri Jan 09, 2004 2:10 pm

hi jack,

thanks a lot for ur answers and even suggestions.you said that now you know y we'de use one instead of the other(IN/OUTFILE IN/OUTDATASET).i too know only how to code them.i dont know y.y dont u answer that plzzzzz.

THANKS AND REGARDS
ANURADHA

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

Hi Anuradha,

I had to code a rather lengthy JCL proc. One step had to delete a file. When testing I found that the file was not always there. If I used INFILE the proc failed w/a JCL error (ds not found) because I had to supply a DD card for the file.

What to do? ......

Boing! What if I used IDS (INDATASET)? No DD card was required .... I wonder... IDCAMS passed an RC of 8 (I think) and the proc continued. AhHa!, so that's why! If you want the JCL to stop (sometimes you don't), use INFILE; if you want to continue executing the JCL, use IDS.

You won't find that in the manual ... at least I didn't.

Regards, Jack.