On Aug 8, 2012, at 09:11, Mike Schwab wrote:
> A zero byte VB record is expanded to 1 blank x'40' so the minimum is a
> block of 9 bytes including block size and record size field.
>
??? No.
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dgt2d490/3.1.3.1.2
Title: z/OS V1R12 DFSMS Using Data Sets
Document Number: SC26-7410-10
3.1.3.1.2 Record Descriptor Word (RDW)
A variable-length logical record consists of a record descriptor
word (RDW) followed by the data. The record descriptor word is a
4 byte field describing the record. The first 2 bytes contain
the length (LL) of the logical record (including the 4 byte
RDW). The length can be from 4 to 32 760. All bits of the third
and fourth bytes must be 0, because other values are used for
spanned records.
A length of 4 implies zero bytes of data; no blank. It's
easy to create such records with EXECIO, FTP, or vi.
I do not find a stated minimum for the BDW. Absent firm
information, I'll assume 4-byte blocks (nothing but BDW)
are permissible.
> I tried to allocate a FB 6 0 to hold a list of volsers for a table,
> LRL under 10 would not work.
>
I had no such problem:
Data Set Information
More: +
Data Set Name . . . . : user.SHORT.BLOCKS
General Data Current Allocation
Management class . . : **None** Allocated blocks . : 86
Storage class . . . : **None** Allocated extents . : 1
Volume serial . . . : TSO005
Device type . . . . : 3390
Data class . . . . . : **None**
Organization . . . : PS Current Utilization
Record format . . . : F Used blocks . . . . : 3
Record length . . . : 6 Used extents . . . : 1
Block size . . . . : 6
Command ===>
F1=Help F3=Exit F12=Cancel
. . . . . . . . . . . . . . . . . . . . . . . . . . .
File Edit Edit_Settings Menu Utilities Compilers Test Help
———————————————————————————————————————————————————————————————————————————————
VIEW user.SHORT.BLOCKS Columns 00001 00006
****** ***************************** Top of Data ******************************
=PROF> ....BLOCKS (FIXED - 6)....RECOVERY OFF WARN....NUMBER OFF...............
000001 these
000002 are
000003 recrds
****** **************************** Bottom of Data ****************************
-- gil
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