You can specify whether a data set is eligible for backup-while-open
(BWO) processing. You can also indicate whether a data set is recoverable
or not, and if so, provide the name of the forward recovery log stream.
Restriction: These
attributes are only available to system-managed data sets.
- BWO
- Specifies whether BWO is to be used. This applies only to system-managed
VSAM data sets, and is not available for linear data sets. Specify
one of the following:
- TYPECICS
- BWO processing is used for CICS® VSAM
file control data sets. SMS rejects dynamic or JCL allocations if,
as the result of an alter function, the value for LOG is changed to
ALL without a logstream ID being available, or if the logstream ID
is nullified.
- TYPEIMS
- BWO processing is used for IMS™ VSAM
data sets.
Note: Support for this option is only available with IMS 6.1 or above.
- NO
- BWO is not used for CICS VSAM
file control or IMS VSAM data
sets. This is the default.
- FRlog
- Specifies whether VSAM batch
logging is to be performed for your VSAM data set. Specify one of
the following:
- ALL
- Tells VSAM to do both forward and backward recovery logging.
Changes made by applications are written to the MVS log stream indicated
on the logstream ID parameter.
- NONE
- Disables the VSAM batch logging function for your VSAM data set.
Changes made by applications are not written to the MVS log
stream indicated on the logstream ID parameter.
- REDO
- Tells VSAM to do forward recovery logging. Changes made by applications
are written to the MVS log stream indicated on the logstream ID parameter.
- UNDO
- Tells VSAM to do backward recovery logging. Changes made by applications
are written to the MVS log stream indicated on the logstream ID parameter.
- blank
- The FRlog value in the catalog is used.
If you specify FRlog(ALL), FRlog(REDO), or FRlog(UNDO),
you must specify the logstream ID parameter for the VSAM data sets.
If you do not specify the logstream ID, message IEC161I is issued.
There is no default JCL value. If FRlog is omitted, the catalog
value is used.
- Log
- Specifies
whether the data set is considered recoverable or not.
For data
sets defined using access method services, the Log and Logstream ID
attributes in the data class are merged with those defined in the
DEFINE command. If a single logstream is to be used for each VSAM
data set, the logstream ID should be specified on the DEFINE command.
Specify the logstream ID in the data class only if the same logstream
ID is to be used for many data sets. Otherwise, this will result in
too many data classes.
Additionally, SMS rejects dynamic or
JCL allocations if, as the result of an alter function, the value
for LOG is changed to ALL without a logstream ID being available,
or if the logstream ID is nullified. Specify one of the following:
- NONE
- Indicates that neither an external backout nor a forward recovery
capability is available, so the data set is not considered recoverable
- UNDO
- Indicates that changes can be backed out using an external log,
so the data set is considered recoverable
- ALL
- Indicates that changes can be backed out and forward recovered
using an external log
If you specify Log(ALL), you must specify
a logstream ID, either on the access method services DEFINE command
or in the Logstream ID field in the data class.
- blank
- The data set is not recoverable. This is the default.
- Logstream ID
- Identifies the CICS forward recovery log stream. It applies
to all components of the sphere. If you specify Log(ALL) or FRlog(REDO),
you must specify a logstream ID.
A logstream ID is made up of 1-to-26
characters, including separators. This name is made up of one or more
segments, each containing one to eight alphabetic, numeric, or national
characters. The first character of each segment must be an alphabetic
or national character. Segments are joined by periods.
For
data sets defined using access method services, the attributes in
the data class are merged with those defined in the DEFINE command.
If a single logstream is to be used for each VSAM data set, the logstream
ID should be specified on the DEFINE command. Specify the logstream
ID in the data class only if the same logstream ID is to be used for
many data sets. Otherwise, this will result in too many data classes.
- Log Replicate
- Specifies whether the data
set is eligible for replication:
- Y
- Yes, data set is eligible for VSAM replication.
- N
- No, data set is not eligible for VSAM replication. This is the
default.