38 IBM VM/370 Planning and System Generation Guide
Planning Considerations for Other Virtual Planning Considerations for Virtual Machine
OperatingSystems (Other than CMS) This section contains information about the following: • The V8/VS Handshaking Feature • Virtual Machines Using the Same Operating System • The RSCS Virtual • Using Channel Switching • Operating Systems Using Reserve/Release
TheVM/VS Handshaking Feature
TheVM/370 and
certain other system control programs (such asOS/VS1) that makes each
system control program aware of certain capabilities and requirements of
the other. TheVM/VS Handshaking feature consists of: • Processing pseudo page faults • Closing VM/370 spool files when the system control program's output
writer operation is complete• Providing an optional nonpaging mode for operating systems executing
under the control ofVM/370 • Providing miscellaneous enhancements for an operating system's
virtual machine executing under the control ofVM/370 A page fault is a program interrupt that occurs when a page that is
marked "not in storage" is referred to by an instruction in an active
page. Thevirtual machine requesting the page is placed in the wait
state while the requested page is brought into real storage. However,
with the
executing under the control ofVM/370 in a virtual machine may dispatch
one task while waiting forV8/370 to honor a page request for another
task.When the pseudo page fault portion of V8/VS Handshaking is
active,V8/370 sends a pseudo page fault (program interrupt X'14') to
the guest system.When the guest system recognizes a pseudo page fault,
it places only the task waiting for the page in page wait and can
dispatch any of its other tasks.Since no paging is done by the operating system using VM/VS handshaking, ISAM programs are treated by
run from fixed storage locations. Therefore, in order to execute theISAM program successfully, the virtual machine directory must include
theISAM option. When the handshaking feature is active, the operating system using VM/VS handshaking closes the CP spool files by invoking the CP CLOSE command when the task or job has completed. Once these spool files are
closed, they can be processed byPart 1. Planning for System Generation 39
Operating
The
The
certain other system control programs (such as
system control program aware of certain capabilities and requirements of
the other. The
writer operation is complete
under the control of
virtual machine executing under the control of
marked "not in storage" is referred to by an instruction in an active
page. The
state while the requested page is brought into real storage. However,
with the
executing under the control of
one task while waiting for
task.
active,
the guest system.
it places only the task waiting for the page in page wait and can
dispatch any of its other tasks.
run from fixed storage locations. Therefore, in order to execute the
the
closed, they can be processed by
