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Local APPC parallel-session and single-session connections initiated
by BIND
If autoinstall is enabled, and an incoming APPC BIND request is received for an
APPC service manager (SNASVCMG) session (or for the only session of a
single-session connection), and there is no matching CICS CONNECTION
definition, a new connection is created and installed automatically.
Like autoinstall for other resources, autoinstall for APPC connections requires model
definitions. However, unlike the model definitions used to autoinstall terminals, those
used to autoinstall APPC links do not need to be defined explicitly as models.
Instead, CICS can use any previously-installed connection definition as a “template”
for a new definition. In order for autoinstall to work, you must have a template for
each kind of connection you want to be autoinstalled.
Autoinstall templates for APPC connections
The purpose of a template is to provide CICS with a definition that can be used for
all connections with the same properties. You customize the supplied autoinstall
control program, DFHZATDY, to select an appropriate template for each new
connection, depending on the information it receives from VTAM.
A template consists of a CONNECTION definition and its associated SESSIONS
definitions. You should have a definition installed for each different set of session
properties you are going to need.
Any installed connection definition can be used as a template, but for performance
reasons, your template should be an installed connection definition that you do not
actually use. The definition is locked while CICS is copying it, and if you have a
very large number of sessions autoinstalling, the delay may be noticeable.
Benefits of autoinstall
Autoinstall support is likely to be beneficial if you have large numbers of APPC
parallel session devices with identical characteristics. For example, if you had 1000
personal computers (PC)s, all with the same characteristics, you would set up one
template to autoinstall all of them. If 500 of your PCs had one set of characteristics,
and 500 had another set, you would set up two templates to autoinstall them.
Restart of any kind should be noticeably faster, especially when large numbers of
terminals are involved.
Savings can also be made on systems management overheads, and on storage, as
autoinstalled resources do not occupy space before they are used.
Requirements for autoinstall
Autoinstall of APPC connections works with any supported release of ACF/VTAM.
You can have only one active autoinstall control program for terminals and
connections. You must specify the name of the active program on the AIEXIT
system initialization parameter. As well as providing function to autoinstall APPC
connections initiated by BIND requests, the sample program, DFHZATDY, provides
the same function for terminal autoinstall as the default control program,
the autoinstall control program for APPC connections
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CICS TS for OS/390: CICS Customization Guide