ILE RPG Programmer's Guide
Commitment Control Locks
On the STRCMTCTL command, you specify a level of locking, either
LCKLVL(*ALL), LCKLVL(*CHG), or LCKLVL(*CS). When your program is operating
under commitment control and has processed an input or output operation
on a record in a file under commitment control, the record is locked
by commitment control as follows:
- Your program can access the record.
- Another program in your activation group or job, with this file
under commitment control, can read the record. If the file is a shared
file, the second program can also update the record.
- Another program in your activation group or job that does not
have this file under commitment control cannot read or update the
record.
- Another program in a separate activation group or job, with this
file under commitment control, can read the record if you specified
LCKLVL(*CHG), but it cannot read the record if you specified LCKLVL(*ALL).
With either lock level, the next program cannot update the record.
- Another program that does not have this file under commitment
control and that is not in your activation group or job can read but
not update the record.
- Commitment control locks are different than normal locks, depend
on the LCKLVL specified, and can only be released by the COMMIT and
ROLBK operations.
The COMMIT and ROLBK operations release the locks on
the records. The UNLOCK operation will not release records locked
using commitment control. For details on lock levels, see the CL and APIs section of the Programming category
in the i5/OS® Information
Center at this Web site - http://www.ibm.com/systems/i/infocenter/.
The number of entries that can be locked under commitment control
before the COMMIT or ROLBK operations are required may be limited.
For more information, see the Recovering your system manual.
Note:
The SETLL and SETGT operations will lock a record in the
same cases where a read operation (not for update) would lock a record
for commitment control.
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