Just when I was going to say we don't see much VSE here...
What DASD do you have that you might expect 123 extents of 1,100 cylinders anyway?
I think you should talk to your technical support and storage mangement people. If they can't help you, I seem to remember finding a couple of useful-looking VSE question sites "out there" a few months ago. Simple with Google.
Most of the references in this forum are probably for Z/OS VSAM and not relevant to VSE which still uses the old VSAM dataspace concept (yuck!). VSE (now z/VSE), wow, takes me back to the late 70's!
A guick Google throws up the following though:
extract from that....
VSE/VSAM Data Organization
VSE/VSAM Fundamentals Page 17 Stev Glodowski (04/12/2010)
Size Limits: (rc x'1C' "No more available extents")
123 volumes per cluster component (data and index).
16 volumes from default model.
4 byte RBA (Relative Byte Address):
4500 – 11000 cylinders on D/T3390 depending on CI-Size and track utilization
Compression can help
'ExtraLargeDataset' or 'XXL' max 286 GB ( No-RBA access )
Clusters are limited to 123 extents per component (Data/Index).
This is normally only a problem if you specify a very small secondary extent.
VSE/VSAM will sub-allocate an extent up to 5 times.
Catalogs, reusable files, and unique files are limited to 16 extents.
Large DASD Support
BIG-DASD supports dasd with up to 10017 cylinders.
FAT-DASD supports dasd with up to 65520 cylinders
Implementation is transparent to existing applications and JCL.
Dasd is flagged in LISTCAT as “BIG-3390” or “FAT-3390”
Automatic for BIG-DASD using FATDASD parm for DEFINE UCAT & SPACE
Allocations converted to CYLINDERS
Minimum data CISIZE increased to 1024 (depending on key size)
BUFSPACE parameter may be increased
Note: RECOVERABLE catalogs are not supported on “large dasd”.
Also worth looking at this IDCAMS manual in the Define Cluster section: