4GB-limit warning message percentage (VSAM_4GB_WARN_MSG_PCT)

The VSAM_4GB_WARN_MSG_PCT function defines the percentage limit and increment at which Advanced Allocation Management will display a warning message when a 4GB-limited, non-extended addressability data sets is extended to a size approaching the 4GB limit for the data set.

Syntax

Read syntax diagramSkip visual syntax diagramVSAM_4GB_WARN_MSG_PCT= ( xx,yy)

VSAM_4GB_WARN_MSG_PCT=(xx,yy)

Where:

xx
is the percentage value (0-99) described as the highest-allocated relative byte address of a data set divided by 4,294,967,295 (4GB – 1) at or above which a warning message will be issued. If this value is defaulted to or specified as zero, a warning message will be issued after each secondary allocation.
yy
is the percentage value (0-99) described as a percentage of the highest possible allocated relative byte address for the data set (4GB – 1) which is added to the highest-relative byte address at which a previous warning message was issued to determine the data set size at or above which the next warning message will be issued. If this value is defaulted to or specified as zero, a warning message will be issued after each secondary allocation after the initial message which was issue as indicated by the xx operand. If adding this value to the value from the previous warning message results in a value of 100 or higher this indicates that the latest extent has increased the size of the data set to a size that is within one interval value from the maximum value of 4GB at which time the warning message will be issued for each new extend.

Default

(0,0)

Environments

ALLOCATE, EXTEND

Usage and processing considerations

This function is supported for all VSAM data set record organizations for all data sets which do not specify the Extended Addressability attribute in the data set’s associated SMS Data Class. For those data sets for which it is not supported the function is ignored.

For supported data sets, following an extend for secondary allocations and primary allocations on a candidate volume a check will be made on the size of the data set as a percentage of the maximum size of 4GB. If the data set size is at or above the percentage specified by the xx operand a warning message will be issued. For subsequent extends made for the life of the associated allocation, the warning message will be issued again when the data set size is at or exceeds a value calculated as the size (defined as the highest-allocated relative byte address) at it existed when the last warning message was issued plus the number of bytes represented by the result of the calculation of the yy percentage operand times the maximum possible size of the data set in bytes relative to zero (4GB - 1).

For example, the function VSAM_4GB_WARN_MSG_PCT=(75,10) would result in the display of a first warning message when the data set is at or exceeds 75 percent of its maximum possible size and additional warning messages when the data set is extended approximately an additional 10 percent of the maximum possible size of the data set.

This function will be performed for supported data sets following any non-initial extent added or adjusted in size by any Advanced Allocation Management function as well as any secondary allocation extend which is intercepted by Advanced Allocation Management but not otherwise handled.

Related keywords

VSAM_4GB_EXT_REDUCE, VSAM_4GB_WARN_MSG

Example

In the following example, VSAM_4GB_WARN_MSG_PCT=(50,0) specifies that the VSAM_4GB_WARN_MSG function message will be displayed after an allocation which causes the size of the data set to exceed 50 percent of its possible maximum size and for each secondary allocation afterward.

* RULE DEFINITIONS
*
DEFAULTS 
 . 
 .
EXCLUDE JOBNAME=ABCJOB1      * Item to exclude from processing
INCLUDE JOBNAME=ABCJOB*      * Item to include in processing
VSAM_4GB_WARN_MSG=ENABLE     * Enable 4GB limit warning message
VSAM_4GB_WARN_MSG_PCT=(50,0) * Issue warnings after 50% full

The EXCLUDE keyword specifies the selection criteria that are to be excluded from Advanced Allocation Management processing. In the example, jobs that have a job name of ABCJOB1 are excluded from Advanced Allocation Management processing. If Advanced Allocation Management encounters an extent allocation for a data set in a job that has a job name of ABCJOB1 and that allocation would cause the size of the associated data set to near 4GB in size, Advanced Allocation Management would not issue a warning message for that extent.

However, if Advanced Allocation Management encounters a job that has a job name that starts with ABCJOB other than ABCJOB1, it would issue a warning message following an extend that would cause the size of the data set to near 4GB in size as directed by the VSAM_4GB_WARN_MSG keyword because the INCLUDE statement specifies that jobs with job names that begin with ABCJOB are to be included in Advanced Allocation Management processing. The message would first be issued after a secondary allocation results in the data set exceeding 50 percent of its maximum possible size and then after each subsequent secondary allocation.