Could this be what you are wanting? I'm not sure.
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/iea2a8b0/16.4
<quote>
With the IARVSERV macro, you can define multiple types of data sharing and
access. As you read this section, use Figure 16-1 in topic 16.1 to see how each
IARVSERV parameter acts on the current state of the data. Each type of data
sharing access is called a specific view of the source data. A view is the way
your program accesses, or sees, the data. You define the view in the
TARGET_VIEW parameter on IARVSERV, by specifying one of the following:
Read-only view (READONLY value) -- where the target data may not be
modified.
Shared-write view (SHAREDWRITE value) -- where the target data can be read
and modified through the view.
Copy-on-write view (UNIQUEWRITE value) -- where the source data
modifications are not seen by other source - sharing programs. Any attempt to
modify the shared source data in this view causes MVS to create a unique target
copy of the affected page for that address or data space.
An example of two different cases:
If the shared data is modified through a SHAREDWRITE view, the
UNIQUEWRITE view gets an unmodified copy of the data. Any remaining views
sharing that data see the modified data.
If the shared data is modified through a UNIQUEWRITE view, the
UNIQUEWRITE view gets the modified copy of the data. Any remaining views
sharing that data see the unmodified data.
Copy-on-write target view (TARGETWRITE value) -- where the target data may
be read and modified through the source view. Any modification of a shared
target page causes MVS to create a unique target copy of the affected page for
that address or data space.
An example for two different cases:
If the shared data is modified through a SHAREDWRITE view, the
TARGETWRITE view sees the modified data.
If the shared data is modified through a TARGETWRITE view, the
TARGETWRITE view sees the modified copy of the data. Any remaining views
sharing that data see the unmodified data.
</quote>
--
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Systems Engineer IV
IT
Administrative Services Group
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> -----Original Message-----
> From: IBM Mainframe Discussion List [mailto:[email protected]]
> On Behalf Of Shmuel Metz (Seymour J.)
> Sent: Friday, December 07, 2012 11:05 AM
> To: [email protected]
> Subject: Re: LOAD and DELETE macro instructions
>
> In <[email protected]>, on
> 12/06/2012
> at 03:49 PM, Paul Gilmartin <[email protected]> said:
>
> >>I wasn't endorsing it, just attempting to clarify what you had in
> >>mind. What I really want is a sharable split module with copy-on-
> write
> >>for one of the data sections.
> >>
> >That's called fork().
>
> No; fork is used to start a child process. What I'm talking about is a
> module that can be automatically shared between unrelated address
> spaces, with private copies of the writable data. Look at the linkage
> segment in Multics for an example of how that works elsewhere, although
> that particular implementation depends on architectural features
> missing from z.
>
> --
> Shmuel (Seymour J.) Metz, SysProg and JOAT
> Atid/2 <http://patriot.net/~shmuel>
> We don't care. We don't have to care, we're Congress.
> (S877: The Shut up and Eat Your spam act of 2003)
>
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