Well, not really.
There is LRECL=X, but besides we have not very strict limitation of
LRECL. It is 32760 or 32767.
First value is limited by JCL syntax, but the second is available when
allocation PS using LIKE= keyword.
Of course one may automagically write segments with custom-created SDWs,
but I would call it cheating.
BTW: The purpose of VBS was not veeeeeeery long record, but records up
to 32k, even on DASD with shorter track. Hint: the track is natural
limit of BLKSIZE. It is no longer important since 3380 (80's), because
track size exceeded 32k.
--
Radoslaw Skorupka
Lodz, Poland
W dniu 16.05.2023 o 18:52, Michael Oujesky pisze:
Just another tidbit, but when combining the record segments, while the
VBS architecture does not specify a maximum record length, you can
expect the full records to be up to 16,777,215 (16384K - 1) bytes in
length.
Realizing that the RDW is actually a SDW.
Michael
At 01:26 AM 5/16/2023, Michael Stein wrote:
On Tue, May 16, 2023 at 04:14:07AM +0000, Prashant Joshi wrote:
>> Did you specify binary mode on the python open call? --
> Yes. And I can read the data.
How are you reading the data. Assuming an open like:
myfile = open("filename", "rb")
You need to either read it all into memory:
alldata = myfile.read()
or read specific lengths which is messier as you need to read specific
lengths, first 4 bytes for the RDW and then the length of the record
in the RDW-4 (as you already read the RDW).
The 4 byte RDW includes the length of the record in the first 2 bytes
(bigendian order) and the spanning bits in the last 2 bytes.
Either way you need to walk your way through the binary data, any code
looking for CR or NL or space isn't correct.
A description of VBS records formats:
z/OS 2.4 DFSMS Using Data Sets SC23-6855-40
https://www-40.ibm.com/servers/resourcelink/svc00100.nsf/pages/zOSV2R4sc236855/$file/idad400_v2r4.pdf
pdf page 273 Variable-Length Record Formats
(near bottom of page and continues on to more pages)
> its just that I don't get proper end of reord. Hence every time I
> read record, I get random record length (multiple records/half records
> combined)
There aren't any "end of records" in a VBS file. At the begining of
the file you know you are at the start of a RDW (Well, BDW/RDW but I'm
assuming the FTP removed the BDWs).
You can find the next record by going the length specified in the RDW
into the file -- that is the start of the next RDW. Continue until
you've processed all the records.
More help will likely require you to show some code and/or data so
we can see what is going on...
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