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what does this mean "dataset should be cataloged"


IBM Mainframe Forums -> JCL & VSAM
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sunny_io

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Joined: 11 Jul 2007
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PostPosted: Sat Apr 12, 2008 2:34 am
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Hello all.

DISP=(NEW,CATLG,DELETE) Disp specifies the disposition of dataset,

NEW - Dataset not exists, need to create
CATLG - If step executed successfully, dataset should be cataloged
DELETE - If any error occurred, Dataset should be deleted

Can somebody pls explain the concept of cataloging ?

and while opening a cataloged dataset , we always give name in single qoute also. is that a convention to identify to look in a specific place for the dataset

thanks
Sunny
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CICS Guy

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Joined: 18 Jul 2007
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PostPosted: Sat Apr 12, 2008 2:44 am
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By being cataloged, the volser of where it resides is known by the catalog and is available without you needing to know where.
Uncataloged datasets would need a volser parameter to tell the system where to find it.
Generally, when referencing a non quoted dataset, your tso userid gets plugged in front of the dataname.
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sunny_io

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PostPosted: Sat Apr 12, 2008 3:01 am
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term volser i understand , should mean address or a pointer.

Pls provide some more info on the term catalog.

Where is it mentained . Is it updated each time we edit / add / delete a file

Can PDS / Datasets / libraries all be cataloged

Use of cataloge

thanks
Sunny
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Balaji Krishnamurthy

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PostPosted: Sat Apr 12, 2008 4:00 am
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IBM mainframe catalog is like an index in a book. It contains the details of all datasets and the volumes in which they reside. So, once you give the parameter as catalog, IBM will put an entry into the system catalog. So, the next time you access the dataset, you just have to specify the data set name and the sysem will pick the volume serial number from the catalog and mounts that volume to read the dataset.
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Mohit Saxena

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Joined: 21 Aug 2007
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PostPosted: Sat Apr 12, 2008 4:26 am
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Quote:
Is it updated each time we edit / add / delete a file


catalog is not updated while we edit a file, it will only be updated on adding/deleting.

Quote:
Can PDS / Datasets / libraries all be cataloged


Yes..
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Anuj Dhawan

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Joined: 22 Apr 2006
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PostPosted: Sat Apr 12, 2008 5:09 am
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My Boy,

Forget about Mainframes, just for some time think for a general meaning of English word "Catalog". Many meanings, such as..directory, index, list...

"Catalog" in Mainframes is no more different, calatlog is the collection of all data set indexes that are used by the control program to locate a volume containing a specific data set.

This goes back to that time when mainframes were not 'rich' enough to understands the whereabouts of a file (DSN). User had to provide the information on which VOLume SERial (DASD or TAPE) my files resides, to overcome this Catalog service came into the picture, when in DISP parameter we use (,CATLG,) system (SMS) makes an entry (like a place holder) in Sytem catalog.
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Anuj Dhawan

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Joined: 22 Apr 2006
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PostPosted: Sat Apr 12, 2008 6:15 am
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Further,

SMS (storage management subsystem) contols datasets allocations on MVS with dataclass storeclass parameters that define DCB.

Before the advent of SMS, you had to supply all DCB and volume information in JCL, and no check was made as to the existance of datasets (it means you could have two datsets residing on different volumes causing troubles in production runs -sometimes) then came the catalog services, you could no longer catalog already cataloged datasets and SMS goes further by relieving the user from supplying DCB (lrecl. blksize, recfm) , volume and space parameters.

Hope this helps.
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