any virtual machine that loads the saved system by name. (In attached
processor mode, there are two sets of pages, page tables, and swap
tables maintained for each shared segment.) A shared segment must be
reenterable and the segment number must be included in the
In the previous example of a
This indicates that segment 1 of
saved, via the
that any user loading
in real storage. This results in a saving of both real and external
page storage. Also, the more virtual machines using the shared segment,
the more likely it is that these pages will be frequently referenced
and, thereby, kept in real storage.
faults and the corresponding time and resources expended in page
swappinq will be reduced.
saved, a problem can occur if the previous system has been loaded by
name and is still in use. If users of the
reference pages that have already been brought into paging storage, no
problems will occur. However, if after the new system has been saved,
users of the old system reference pages that had not previously been
referenced, they receive the
Any users who
the shared segment.
Also, the entire segment is saved by the
that portion occupied by the program (for example,
The use of shared segments is not allowed in a virtual=real machine.
The maximum number of shared segments that may be defined is 78.
with discontiguous saved segment support, you can attach and detach
segments of storage to and from your virtual machine. These segments
contain reenterable code that can be shared by many users. Thus,
programs that are required
shared and only loaded when they are needed.