The Question is:
Usage of SYSGEN GBLPAGFIL?
In order to see what is going on, $INSTALL does provide some (incomplete)
information about GBLPAGES. $INSTALL
L/G/SUMM does tell me gblpages in use/total and
the gblsections in use (omitting the number of total section available). The
number of GBLSECTIONS can be found MCR SYSGEN show GBL*.
GBLPAGFIL is set to some value, how can I find out something about the actual
usage in the running system of this value (to make sure the value is suffient
and not excessive)?.
It would be very nice, if INSTALL could simply show all these values in the
summary statement in a reasonable way.
winfried h. oppermann
The Answer is :
INSTALL is the user command interface into the image activator,
and is not particularly intended as a mechanism for monitoring
system page file usage. The mechanisms underneath INSTALL do use
global sections and the global section system services, but these
installed sections are typically file-backed sections, and not
Global sections (created via INSTALL or via system service) will
clearly use GBLPAGES and GBLSECTS, but the underlying page table
data structures are small and thus reasonable overconfigurations
of these parameters are not particularly wasteful of memory.
The GBLPAGEFIL prevents excess use of the pagefile, but having
sufficient pagefile configured is also not particularly wasteful
of resources given the current costs of large-scale disk storage.
For information on the system configuration, please see the $getsyi
service (or f$getsyi lexical) and FREE_GBLPAGES, CONTIG_GBLPAGES,
FREE_GBLSECTS, PAGEFILE_FREE, PAGEFILE_PAGE, etc.
In the specific case of the GBLPAGFIL parameter, this is a dynamic
parameter that controls the amount of pagefile that can be allocated
for use as backing storage for global sections, meaning that the
PAGEFILE_FREE and PAGEFILE_PAGE parameters would be among the most
interesting, as well as (obviously) the DCL command SHOW MEMORY.
If you wish to reduce the amount of storage used in the pagefile,
you can use file-backed sections.
Some of the related topics include (7752), (6536), and (5002).