For each structure that is to be eligible for system-initiated
alter processing, the following parameters in the CFRM policy can
be specified:
- ALLOWAUTOALT
Specify ALLOWAUTOALT(YES) to request
that the structure be eligible for system-initiated alter processing.
For structure alter processing to be started for a structure, alter
must be permitted (see the SETXCF MODIFY command) and the exploiter
must also allow alter. The ALLOWAUTOALT specification affects the
default value for MINSIZE.
The ALLOWAUTOALT specification takes
effect immediately when the updated CFRM policy is activated.
ALLOWAUTOALT(NO)
is the default value.
- FULLTHRESHOLD
The value you assign to the FULLTHRESHOLD parameter
is used by both Structure Full Monitoring and system-initiated alter
processing. The value is specified as a percentage and represents
a percent full threshold in terms of coupling facility structure objects.
See Monitoring structure utilization. If a value of zero is assigned to FULLTHRESHOLD,
neither structure full monitoring nor automatic altering of the structure
will occur. If a value other than zero is specified or defaulted to,
the value is used as the percent full threshold for structure full
monitoring as well as being used by system-initiated alter processing
to determine how to alter the structure if the exploiter allows alter.
If the exploiter does not allow alter, the ALLOWAUTOALT specification
is ignored and a non-zero value for FULLTHRESHOLD is used only by
Structure Full Monitoring to alert the installation.
The FULLTHRESHOLD
specification takes effect immediately when the updated CFRM policy
is activated.
80% is the default value for FULLTHRESHOLD.
- MINSIZE
The value you assign to MINSIZE specifies the smallest
size to which the structure can ever be altered, either as a result
of system-initiated alter or any alter process (operator command or
programming interface). This value also serves as a minimum bound
for the structure size on all structure allocation requests (including
connect and rebuild connect) with the following exception. During
system-managed rebuild, new structure allocation may result in the
structure being allocated with a size smaller than the value specified
or defaulted to for MINSIZE. See How MVS initially allocates the structure for information
about structure allocation during system-managed rebuild.
The MINSIZE value must be less than or equal to the INITSIZE
value, or less than or equal to the SIZE value if INITSIZE is not
specified. If ALLOWAUTOALT(YES) is specified and MINSIZE is not specified,
the system will use a value of 75% of INITSIZE, or 75% of SIZE if
INITSIZE is not specified, as the MINSIZE value. Otherwise, if ALLOWAUTOALT(NO)
is specified or defaulted to and MINSIZE is not specified, the system
will use a value of zero for MINSIZE.
Note that
in order for the MINSIZE value to take effect in the sysplex, a newly-activated
CFRM policy will remain pending until any allocated structures with
a MINSIZE value other than zero have been rebuilt to reflect the policy
change. (For structures that are not allocated, the policy change
can take effect immediately.) For those allocated structures, you
are required to either deallocate or reallocate the structure or
issue SETXCF START,REBUILD,STRNAME=strname before the policy change
takes effect for the structure.