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The following access method services examples assume that CICS.DATASET.A needs
to be redefined and the data moved to a data set named CICS.DATASET.B, which is
then renamed:
DEFINE CLUSTER (NAME(CICS.DATASET.B) ...
REPRO INDATASET(CICS.DATASET.A) OUTDATASET(CICS.DATASET.B)
DELETE CICS.DATASET.A
ALTER CICS.DATASET.B NEWNAME(CICS.DATASET.A)
If the recoverable data set has associated RLS locks, these steps are not sufficient
because:
v The REPRO command copies the data from CICS.DATASET.A to
CICS.DATASET.B but leaves the locks associated with the original data set
CICS.DATASET.A.
v The DELETE command deletes both the original data set and its associated
locks.
v After you issue the ALTER command, the data set has been moved but the new
data set does not have any associated locks, which have been lost when you
deleted the original data set.
To enable you to move data and keep the locks associated with the data, access
method services provide the following SHCDS subcommands. These are
subcommands of the VSAM sharing control SHCDS command and must always be
preceded by the SHCDS keyword:
SHCDS FRSETRR
This command marks the data set as being under maintenance, by setting a
flag in the data set’s ICF catalog entry. (This flag is shown as ‘Recovery
Required’ in a catalog listing (LISTCAT).)
SHCDS FRUNBIND
This command unbinds any retained locks held against the data set. The locks
are no longer associated with any specific disk location or data set.
SHCDS FRBIND
This command re-binds to the new data set all retained locks that were
unbound from the old data set. The locks are now associated with the named
data set. The data set name used in FRBIND must match the name used in the
earlier FRUNBIND.
SHCDS FRRESETRR
This frees the data set from being under maintenance, resetting the flag in the
ICF catalog.
Based on the above example of using REPRO to move a VSAM data set, the
complete solution for a data set accessed in RLS mode, and which preserves the
RLS locks, is as follows:
Procedure
1. Quiesce the data set that is being moved, to prevent access by CICS regions
while maintenance is in progress.
2. Create a new data set into which the data is to be copied. At this stage, it
cannot have the same name as the old data set. For example:
DEFINE CLUSTER (NAME(CICS.DATASET.B) ...
3. Issue the access method services (AMS) SHCDS FRSETRR subcommand to
mark the old data set as being under maintenance. For example:
SHCDS FRSETRR(CICS.DATASET.A)
184 CICS TS for z/OS 4.1: Recovery and Restart Guide