A tricky file handling option in CICS is CONSISTENT. CICS handles integrity in two ways. There are two ways -One way is read waits till update completes, and option -2 is first READ completes and then UPDATE completes.
Details of CICS READ
The record is read with a level of read integrity provided by a VSAM shared lock that lasts for the duration of the request.
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If the record is being modified by another task, which therefore holds an exclusive lock, the READ request waits until the update is complete (unless NOSUSPEND is also specified) as follows:
- For a READ request against a non-recoverable file, the READ completes as soon as any VSAM request performing the update completes.
- For a READ request against a recoverable file, the READ request completes when the updating task completes its next sync point or rollback.
CICS READ Syntax from IBM manual:
READ--FILE(filename)--+------------------------------+------->
+-UNCOMMITTED------------------+
+-CONSISTENT-------------------+
+-REPEATABLE-------------------+
'-UPDATE--+------------------+-'
'-TOKEN(data-area)-'
>--+-INTO(data-area)-+--RIDFLD(data-area)----------------------->
'-SET(ptr-ref)----'
>--+------------------------------------+----------------------->
'-KEYLENGTH(data-value)--+---------+-'
'-GENERIC-'
>--+--------------------------------------+--+--------+--------->
+-SYSID(systemname)--LENGTH(data-area)-+ +-DEBKEY-+
'-LENGTH(data-area)--------------------' +-DEBREC-+
+-RBA----+
+-RRN----+
'-XRBA---'
.-EQUAL-.
>--+-------+--+-----------+------------------------------------><
'-GTEQ--' '-NOSUSPEND-'
Srinimf 