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leoben
New User
Joined: 21 Mar 2023
Posts: 4
Location: United Kingdom
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Hi all,
I'm currently trying to wrap my head around how I can accurately calculate the size I need to allocate to a data set when writing output from the spool via the xdc command. My device type is 3390.
The spool output i'm currently working with has the following:
| Code: |
Rec-Cnt 01 5,183
Byte-Cnt 01 77,209
LRecL 01 251
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When I allocate a data set using KB as my space unit, I get the following:
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Current Allocation
Allocated kilobytes : 709
Allocated extents . : 12
Current Utilization
Used kilobytes . . : 681
Used extents . . . : 12
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When I switch to tracks, I get the following:
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Current Allocation
Allocated tracks . : 13
Allocated extents . : 9
Current Utilization
Used tracks . . . . : 13
Used extents . . . : 9
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Based on some of the reading I've done, each track should be 56664 bytes for a 3390 disk type. The 681 KB thus seems to match up with the 13 tracks (as 12x56664 would not be enough).
Is there anyway I can determine the size i need from the Rec-cnt, Byte-cnt and LREC. Happy to be pointed to any resources, I've just exhausted my own Googling abilities.
Thanks in advance. |
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sergeyken
Senior Member
Joined: 29 Apr 2008
Posts: 2023
Location: USA
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1. The actually used disk space seriously depends on your BLKSIZE. If BLKSIZE is small (e.g. is equal to a single LRECL) then too many interblock gaps do appear along the track, which leads to loose of space. In you situation use BLKSIZE=25100 (for RECFM=FB), or BLKSIZE=25104 (for RECFM=VB), or BLKSIZE=0 (to allow zOS calculate adequate BLKSIZE for you).
2. You can specify required space in terms of bytes you need.
SPACE=(blksize,(primary,secondary),RLSE)
blksize is the physical record = block size in bytes. |
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Willy Jensen
Active Member
Joined: 01 Sep 2015
Posts: 712
Location: Denmark
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I just tried XDC with defaults except from blksize 0, it gave me a dataset allocated as VBA 240 244, which is not good. It might of course be down to the ACS routines at that particular site. Since you say that you are using the SDSF XDC command, I will suggest that you instead allocate with lrecl 27994 and bksize either 0 or 27998. As to the space, try with TRKS 8, 15 and see what happens.
You will probably use the dataset for other output in the future, so just make it big enough. |
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