z/OS® DFSMS V2R2 provides the following enhancements
to the object access method (OAM):
- System-managed tape enhancements for the TS7700:
Enhancements for Release 3.2 of the TS7700 Virtualization Engine,
which include a new tape attach feature for the TS7720, as well as
support for 496 devices per distributed library. Support for the
added devices also involves doubling the number of allowed subsystems
on a scratch allocation request from 253 to 506 and a new DEVSUPxx
PARMLIB option (GREATER_253). For more information, refer to z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Tape Libraries.
- The OSREQ application programming interface now allows
OAM applications to provide object data buffers in 64-bit addressable
virtual storage above the 2G "bar" when storing object data using
the OSREQ STORE function or when retrieving object data using the
OSREQ RETRIEVE function. These buffers can be used for objects from
1 byte to 2000M for all destinations in the OAM storage hierarchy:
DB2 (4K, 32K, LOB), file system, tape, and optical (with the existing
restriction of a maximum object size of 256M for optical); this includes
the source system handling in OAMplex configurations for objects less
than or equal to 50M for optical writes and reads and tape reads that
are routed to another system in the OAMplex . The ability to use
64-bit addressable virtual storage buffers above the 2G "bar" on
the OSREQ application programming interface can provide virtual storage
constraint relief for OAM applications that have difficulty acquiring
sufficient virtual storage within a 2G address space.
This new
functionality can be used as an alternative to:
- Storing an object up to 2000M in parts with the OSREQ store sequence
functions (STOREBEG/STOREPRT/STOREEND) where multiple OSREQ API invocations
are required and the maximum size for each part is limited by the
practical amount of virtual storage available below the 2G "bar" for
each STOREPRT API invocation
- Retrieving an object (or a partial object) with OSREQ RETRIEVE
where multiple OSREQ API invocations are required and the maximum
size for each retrieve request is limited to 256M
Therefore, this new functionality could also improve the efficiency
of the interactions with OAM through the OSREQ application programming
interface, because only a single OSREQ API invocation is needed to
store an object up to 2000M in size or to retrieve an object up to
2000M in size.
This new functionality includes:
- TSO/E OSREQ command processor changes for STORE and RETRIEVE functions
- OSREQ macro changes for the STORE and RETRIEVE functions and associated
new reason codes
- CBROSR2 sample program changes in support of the OSREQ macro changes.
Notes: - The OSREQ application programming interface remains AMODE 31.
- The maximum possible OAM object size remains unchanged at 2000M.