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Husna
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Joined: 02 Jun 2006
Posts: 49
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Hi,
Could you please clarify the following concept?
For Fixedblock: DSN=(RECFM=FB,LRECL=80,BLKSIZE=800)
LRECL =80 and it takes multiples of it (80*10=800) for BLKSIZE
In the case of Variable:
DSN=(RECFM=VB,LRECL=84,BLKSIZE=840)
LRECL =80 (Plus 4 for Variable length record) and it takes multiples of it (84*10=840) for BLKSIZE
In LRECL we need to mention 80 or 84?
Will you please let me know answer for the same?
Awaiting your reply. |
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prashantshinde
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Joined: 25 Nov 2005
Posts: 49
Location: Pune
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You wrote :
DSN=(RECFM=VB,LRECL=84,BLKSIZE=840) ???
Firstly you should write 'DCB' instead of 'DSN' for defining DCB parameters.
The LRECL for Variable Block record format should be 80,as the 4 bytes for address and length of record are managed internally. |
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Husna
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Joined: 02 Jun 2006
Posts: 49
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Prashant,
Thanks for the reply.
You wrote:
The LRECL for Variable Block record format should be 80,as the 4 bytes for address and length of record are managed internally.
Could you please let me know about BLKSIZE? |
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kondakonda
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Joined: 20 Mar 2006
Posts: 34
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Hi,
For this example,
DCB=(LRECL=80,RECFM=VB,BLKSIZE=84)
Internally each record is stored with maximum length of 84 (4 bytes for record length)
as the BLKSIZE=84 there wont be any unused space
For this example,
DCB=(LRECL=80,RECFM=VB,BLKSIZE=88)
there will be 4 bytes of unused space for every block.
We can define like anything but should always prefer to avoid unused space.
Thanks. |
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prashantshinde
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Joined: 25 Nov 2005
Posts: 49
Location: Pune
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| Husna wrote: |
Could you please let me know about BLKSIZE? |
[red]BLKSIZE[/red] :
In the context of JCL BLKSIZE is same as u have written ..like multiple of LRECL . You would find it more iteresting with COBOL and VSAM
See the attachment |
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Frank Yaeger
DFSORT Developer
Joined: 15 Feb 2005
Posts: 7129
Location: San Jose, CA
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| Quote: |
| LRECL =80 (Plus 4 for Variable length record) and it takes multiples of it (84*10=840) for BLKSIZE |
For VB, the BLKSIZE can be any value greater than or equal to LRECL+4. The BLKSIZE does NOT have to be a multiple of LRECL+4. So for an LRECL of 80, the BLKSIZE can be 84 or greater. Usually, the system determined BLKSIZE (SDB) is a good choice (approx. half-track for DASD = 27998 on a 3390 for LRECL=80). A small BLKSIZE like 84 is not an efficient choice. |
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raviprasath_kp
Warnings : 1
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Joined: 20 Feb 2005
Posts: 65
Location: chennai
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| any one can advice me what is the main diffence between FB VB |
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Frank Yaeger
DFSORT Developer
Joined: 15 Feb 2005
Posts: 7129
Location: San Jose, CA
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With F, all of the records are the same length as defined by the LRECL.
With V, records can be different lengths up to the maximum as defined by the LRECL.
F or V indicates that the records are unblocked. FB or VB indicates that the records are blocked. |
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