A VSAM data set is limited to 4 GB across all volumes unless Extended
Addressability is specified in the SMS data class definition. System
requirements restrict the number of volumes that can be used for one
data set to 59.
Using
extended addressability, the size limit for a VSAM data set is determined
by either:
- Control interval size multiplied by 4 GB
- The volume size multiplied by 59.
A control interval size of 4 KB yields a maximum data set size
of 16 TB, while a control interval size of 32 KB yields a maximum
data set size of 128 TB. A control interval size of 4 KB is preferred
by many applications for performance reasons. No increase in processing
time is expected for extended format data sets that grow beyond 4
GB. To use extended addressability, the data set must be
either: - A VSAM linear data
set (LDS), starting in z/OS V2R1, or
- SMS-managed and defined as extended format.