2. PLANNING › 2.5 Special Considerations › 2.5.5 Multi-Image Manager (MIM) Considerations

2.5.5 Multi-Image Manager (MIM) Considerations

The Multi-Image Manager (MIM) product from CA can intercept
hardware RESERVEs and translate them into less restrictive
ENQs on other MVS images in a shared environment.  This is a
normal function of MIM but the default processing of MIM is
to NOT perform this function when the major name associated
with the serialization request is SYSVTOC.

Appendix A in the MIM Integrity System Guide describes why
SYSVTOC is normally omitted from the QNAME list (MIM will not
change the RESERVE into a global ENQ).  The reasoning is that
programs needing to serialize on SYSVTOC do so only for a
brief period (only for few seconds); thus it is better to
avoid the overhead of propagating ENQs to all connected
system images.

VCC conforms to these guidelines in MIM.  Under normal
circumstances VCC processing is sufficiently fast that the
SYSVTOC resource is only RESERVEd for a few seconds.  Thus,
the default setup of MIM is good for VCC when SERIALIZE=Y is
specified (remember that SERIALIZE=N will not ENQ on SYSVTOC,
therefore RESERVEs are never an issue).

Section 3.1.1.2 of this guide provides details about these
options.

Note that if you do choose to override the default for MIM
and add SYSVTOC to the MIM control file, you must also add
several other major names to the MIM control file:

    o  SYSZVVDS
    o  SYSZRACF
    o  SYSIGGV2
    o  ARCBACV (if DFHSM is operational)
    o  ARCMIGV (if DFHSM is operational)
    o  DSPURI01 (if IMS is operational)

The above list is supplied as a warning for the
considerations regarding SYSVTOC serialization imposed by VCC
in a MIM environment.  Always see the MIM documentation for
the latest information on other considerations related to
SYSVTOC.