2. PERFORMANCE REPORTING ANALYSIS › 2.2 Real Storage Management Analysis › 2.2.4 MVS Concepts › 2.2.4.4 Expanded Storage Concepts › 2.2.4.4.3 Users of Expanded Storage

2.2.4.4.3 Users of Expanded Storage

The RSM categorizes expanded storage use by the type of
paging group and by the status of the page being considered
for placement in expanded storage.  The paging group can be
a:

    Type 0 - Privileged or non-swappable (including all
             common areas) address space,

    Type 1 - Any other type of page not included in types 0
             or 2, or

    Type 2 - A page belonging to a TSO user waiting for
             terminal I/O to complete, or pages paged-out or
             stolen from a TSO user.

The page's status is categorized as a:

    Changed paged-out page
    Changed swapped-out page
    Changed stolen page
    Unchanged paged-out page
    Unchanged swapped-out page
    Unchanged stolen page
    Working set page ready for swap-out
    Virtual fetch page
    VIO swapped-out page
    Hiperspace page

NOTE:  Hiperspaces were introduced with MVS/ESA, and are not
       available in MVS/XA.   The use of expanded storage for
       VIO was standardized in MVS/ESA, but is available in
       MVS/XA systems by means of applying IBM APAR YA09186.

Different criteria ages can be specified for each combination
of paging type and page status, with the exceptions of
virtual fetch, VIO, and hiperspace pages.  The exceptions
have a single criteria age specification without paging type
classification differences.  This allows the installation to
tailor the configuration so that expanded storage usage is
prioritized by the type of address spaces that are most
important in the specific processor complex.  It is possible
to set the parameters so that some of the combinations are
eligible and others ineligible to use expanded storage.