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meetsrk
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Joined: 13 Jun 2004
Posts: 85
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hi ppl,
what is the max. no of DD statements that can used in concatenation? |
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unna
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Joined: 15 Oct 2004
Posts: 17
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Hi,
255 Sequential datasets can be concatenated together
and 16 PDS can be concatenated together.
Have a nice day! |
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superk
Global Moderator
Joined: 26 Apr 2004
Posts: 4652
Location: Raleigh, NC, USA
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unna, would you please be so kind to cite your source for your post (it is incorrect)?
According to the "MVS JCL Reference Guide (SA22-7597-06)", page 12-1:
"The maximum number of DD statements per job step is 3273, based on the number of single DD statements allowed for a TIOT (task input output table) control block size of 64K. This limit can be different depending on the installation-defined TIOT size." |
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unna
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Joined: 15 Oct 2004
Posts: 17
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Hi Superk,
Thank You for pointing out.
By the way, the question is
hi ppl,
what is the max. no of DD statements that can used in concatenation?[/b]
for this i had given the answer.
Kindly,clarify if iam wrong again---
Have a nice day! |
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vishal_09
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Joined: 16 Feb 2005
Posts: 6
Location: hyderabad
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hi .
maximum no of dd staement in jal are 3273........
i concatination u can use only 255 dd staements |
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superk
Global Moderator
Joined: 26 Apr 2004
Posts: 4652
Location: Raleigh, NC, USA
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Folks, again, it would be nice if you would cite your sources for your answers.
I just finished running a job with one step that had 1000 CONCATENATED DD statements without any problems. I might go back and try it again with 3273 CONCATENATED DD statements.  |
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muthukumarapandian
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Joined: 08 Oct 2004
Posts: 42
Location: chennai, india
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Hi meetsrk,
max dd sttements are 3273 and it depends on TIOT control block size specified at the time of installation |
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mmwife
Super Moderator
Joined: 30 May 2003
Posts: 1592
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Hi People,
PLEASE!!! The ques was:
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what is the max. no of DD statements that can used in
*****************
*CONCATENATION*?
*****************
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mcmillan
Site Admin
Joined: 18 May 2003
Posts: 1210
Location: India
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Dear MMWife,
The maximum number of DD statements per job step is 3273. The limit of 3273 is applicable to the concatenation also. But it depends on the pgm that is going to read the concatenated datasets. For example the SEARCH Utility program can only read upto 4 concatenated datasets.
The limit 3273 is also based on the number of single DD statements allowed for a TIOT as Superk mentioned.
Your installation may not allow you to concatenate upto 3273 DDs, coz the IBM-supplied default TIOT size is 32K. You need 64K TIOT to accept 3273 DDs in a single job.
So if you have 64K TIOT, you can use 3273 DDs per job (may be in a single step).
If you have 32K TIOT, you can concatenate upto 1635 DDs.
For 16K, upto 819 DDs supported, I hope...
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255 Sequential datasets can be concatenated together and 16 PDS can be concatenated together |
But in some books, they have mentioned like this. (It's wrong, as for as I know) |
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dharmendra_kp
New User
Joined: 10 Mar 2005
Posts: 33
Location: Lewiston
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hi all!
Can any one tell How / where do we use concatenation in real time .
PLZ illustrate with an example. |
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superk
Global Moderator
Joined: 26 Apr 2004
Posts: 4652
Location: Raleigh, NC, USA
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I found a reference that hopefully answers this question. The document is "z/OS V1R6.0 DFSMS: Using Data Sets":
publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/DGT2D430/CCONTENTS?DT=20040624112123
Section "3.6.3 Concatenating Data Sets Sequentially":
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The system can retrieve two or more data sets and process them successively as a single sequential data set. This is called sequential concatenation. The number of data sets that you can concatenate with sequential concatenation is variable. It is governed by the maximum size of the TIOT option. The system programmer controls the TIOT size with the option ALLOCxx member of SYS1.PARMLIB. The smallest TIOT value allows 819 single-unit DD statements or 64 DD statements having the maximum number of units.
When data sets are sequentially concatenated, your program is open to only one of the data sets at a time. Concatenated data sets cannot be read backward.
A sequential concatenation can include sequential data sets, PDS members, PDSE members, and UNIX files. With sequential concatenation, the system treats a PDS, PDSE, or UNIX member as if it were a sequential data set.
Rule: You cannot concatenate VSAM data sets.
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And section "3.7.8 Concatenating PDSs":
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3.7.8.1 Sequential Concatenation
To process sequentially concatenated data sets, use a DCB that has DSORG=PS. Each DD statement can include the following types of data sets:
Sequential data sets, which can be on disk, tape, instream (SYSIN), TSO terminal, card reader, and subsystem
UNIX files
PDS members
PDSE members
You can use sequential concatenation (DSORG=PS in DCB) to sequentially read directories of PDSs and PDSEs.
3.7.8.2 Partitioned Concatenation
Concatenated PDSs are processed with a DSORG=PO in the DCB. When PDSs are concatenated, the system treats the group as a single data set. A partitioned concatenation can contain a mixture of PDSs, PDSEs, and UNIX directories. Partitioned concatenation is supported only when the DCB is open for input.
There is a limit to how many DD statements are allowed in a partitioned concatenation. Add together the number of PDS extents, the number of PDSEs, and the number of UNIX directories in the concatenation. The sum cannot exceed 255. For example, you can concatenate 15 PDSs of 16 extents each with 8 PDSEs and 7 UNIX directories ((15 x 16) + 8 + 7 = 255 extents).
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