IBM SC34-7012-01 - Manual (Page 218)

How you request BWO
You can define files as eligible for BWO in one of two ways.
Procedure
Decide which method you want to use for data sets:
v If your data set is accessed in RLS mode, you must define the BWO option in
the ICF catalog. Defining BWO in the ICF catalog requires DFSMS 1.3.
v If your data set is accessed only in non-RLS mode, you can define the BWO
option in either the ICF catalog or the CICS file definition.
Defining BWO in the ICF catalog requires DFSMS 1.3. For data sets that are
accessed in RLS mode, the BWO option must be defined in the ICF catalog.
Recovery attributes for data sets that are accessed only in non-RLS mode can be
defined either in the ICF catalog or in the CICS FILE resource. If BWO is defined
in the ICF catalog definition, by default it overrides any BWO option defined in
the FILE resource. To force CICS to use the FILE resource attributes instead of the
catalog recovery options, set the NONRLSRECOV system initialization parameter to
FILEDEF.
Results
Do not define BWO for the CICSPlex SM data repository using the IDCAMS
DEFINE CLUSTER definition in the ICF catalog because performance is degraded.
See the CICS Transaction Server for z/OS Installation Guide for information on taking
backups of the CICSPlex SM data repository.
Specifying BWO using access method services
There is a BWO parameter on the access method services DEFINE CLUSTER
statement.
About this task
You can specify the BWO parameter as follows:
TYPECICS
The data set is eligible for BWO in CICS.
NO The data set is not eligible for BWO.
TYPEIMS
The data set is eligible for BWO in IMS, but CICS treats this as NO.
TYPEOTHER
The data set is eligible for BWO, but CICS treats this as NO.
If you specify BWO(TYPECICS), you might need to know whether the PTF
associated with APAR OA04220 has been applied to your z/OS system. That APAR
extended the capabilities of VSAM so that BWO processing for RLS is no longer
disabled for non-recoverable files.
v If you specify BWO(TYPECICS), and you have also specified LOG(ALL) and a
forward recovery log stream name, LOGSTREAMID(logstream_name), your file is
recoverable, and the status of the PTF is not important.
v If you specify BWO(TYPECICS), and the PTF has been applied, BWO processing
is now enabled for all VSAM RLS files whether you have specified LOG(ALL),
LOG(NONE) or LOG(UNDO).
206 CICS TS for z/OS 4.1: Recovery and Restart Guide