Gerhard Hellriegel posted the following:
> Hi all your zOS freaks,
> maybe someone has a idea: we have very big SAS libraries with
> multi-volume and many extents. The data-volume is growing
> inside that library. We need to know, when we are close to a
> limit, means, how high is the space limit for a specific
> library. PROC CONTENTS returns only the current formatted
> blocks, which is not the space, zOS can allocate for that
> library. Maybe the FCB for the file can give us that
> information. Means: I would know the extents, which can be
> allocated and their max size. I know, that this is only half
> of the truth, because the space might not be available
> anyway, but better that knowing nothing. Does anyone know,
> how to get this? If it is not possible in SAS, maybe someone
> knows if that is provided by DCOLLECT? Please share your
> experience! Thanks for your input! Gerhard
Gerhard, hey; who are you calling a "freak"?!?!?!?!:-)
Well, I see that the MVS experts have already provided their usual high level of sage advice. I would just chime in with something that you probably already know--but some other readers may not: make sure to use 1/2 track blocking on your DASD for very large SAS data sets. The block size of 27,468 ensures that the greatest possible amount of space on a track is used; reducing the overall footprint of the SAS data set. It also promotes good performance as those SAS data set pages are dragged from DASD to computer memory; taking with them large amounts of observations.
SAS refers to SAS data set blocks as "SAS data set pages". SAS page size (block size) is controlled via the BUFSIZE system or data set option. Whatever value of BUFSIZE is in effect when a SAS data set is first created determines the BUFSIZE (block size) of the SAS data set. So, having:
...at the top of a SAS program ensures that SAS data sets created in that program all have the SAS page size of 27,648 bytes.
Gerhard, best of luck with your _BIG_ SAS data sets!
I hope that this suggestion proves helpful now, and in the future!
Of course, all of these opinions and insights are my own, and do not reflect those of my organization or my associates. All SAS code and/or methodologies specified in this posting are for illustrative purposes only and no warranty is stated or implied as to their accuracy or applicability. People deciding to use information in this posting do so at their own risk.
Michael A. Raithel
"The man who wrote the book on performance"
Author: Tuning SAS Applications in the MVS Environment
Author: Tuning SAS Applications in the OS/390 and z/OS Environments, Second Edition
Author: The Complete Guide to SAS Indexes
He attacked everything in life with a mix of extraordinary genius and na´ve incompetence,
and it was often difficult to tell which was which. - Douglas Adams