For those still in doubt, here's a one track PDS with one directory block.
_____________________________________________________________________
Data Set Information
Command ===>
Data Set Name . . . : ASE.V2DEV.ONETRK
General Data Current Allocation
Volume serial . . . : ASE001 Allocated tracks . : 1
Device type . . . . : 3380 Allocated extents . : 1
Organization . . . : PO Maximum dir. blocks : 1
Record format . . . : FB
Record length . . . : 80
Block size . . . . : 3120 Current Utilization
1st extent tracks . : 1 Used tracks . . . . : 1
Secondary tracks . : 0 Used extents . . . : 1
Used dir. blocks . : 1
Creation date . . . : 2007/05/20 Number of members . : 2
_____________________________________________________________________
EDIT ASE.V2DEV.ONETRK Row 000
Command ===> Scrol
Name Prompt Size Created Changed
. ONE 1 2007/05/20 2007/05/20 21:16:55
. TWO 1 2007/05/20 2007/05/20 21:17:27
_____________________________________________________________________
..and here's the one and only directory block:
(note: 8 byte hardware key field preceeding this block is x'ffffffffffffffff')
===> BLOCK# 1
0000(+0000) 0062 <--- each used dir blk starts with halfword
"offset-to-freespace"
... 1st directory entry, for member "ONE " ...
D6D5 C5404040 40400000
030F0100 | ONE | member TTR=0000 03
0016(+0010) 00550107 140F0107 140F2116 00010001 | |
0032(+0020) 0000C7D9 C1C5D4C5 40404040
... 2nd directory entry, for member "TWO " ...
E3E6D640 | GRAEME TWO |
0048(+0030) 40404040 0000050F 01000027
0107140F | | member TTR=0000 05
0064(+0040) 0107140F 21170001 00010000 C7D9C1C5 | GRAE|
0080(+0050) D4C54040 4040
... the 12 byte end-of-directory entry, key x'FFFFFFFFFFFFFFFF' ...
FFFF FFFFFFFF FFFF0000 |ME |
0096(+0060) 0000
... rest of the block is free space ...
0000 00000000 00000000 00000000 | |
0112(+0070) 00000000 00000000 00000000 00000000 | |
0128(+0080) 00000000 00000000 00000000 00000000 | |
0144(+0090) 00000000 00000000 00000000 00000000 | |
0160(+00A0) 00000000 00000000 00000000 00000000 | |
0176(+00B0) 00000000 00000000 00000000 00000000 | |
0192(+00C0) 00000000 00000000 00000000 00000000 | |
0208(+00D0) 00000000 00000000 00000000 00000000 | |
0224(+00E0) 00000000 00000000 00000000 00000000 | |
0240(+00F0) 00000000 00000000 00000000 00000000 | |
REACHED EOF <--- there's an EOF following the directory block,
it's rec 2 on the track.
Rec 3 on the track is the data block for member "ONE"
Rec 4 .. is the EOF for member "ONE"
Rec 5 on the track is the data block for member "TWO"
Rec 6 .. is the EOF for member "TWO"
Regards to all,
Graeme
At 04:10 AM 5/13/2007, various persons wrote:
<snip>
I tested this in the old days of SLED DASD, and the directory was a
keyed track and you COULD NOT store a member in the directory track. It
always took 2 tracks minimum for a PDS (of course, this has not been
true for about 15 years).
<snip>
I agree with (the other) Tom - I don't think this has ever been true.
I just tried making a member in a new single track PDS under MVS 3.8
and it worked without a problem - and that software is more than
20 years old.
<snip>
All I can tell you is that I tested this on an old 3380 circa 1994
with MVS 4.2(? so long ago not sure anymore). Nothing other than
the directory was stored on the first track. I then tested on a
RAMAC2, but no problem creating a 1-track PDS and storing a
member. If I'm wrong, I'm wrong, but that's what I remember.
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