Autoinstalling programs--preliminary considerations

As well as terminals and APPC connections, you can autoinstall:

If the autoinstall program function is enabled, and an implicit or explicit load request is issued for a previously undefined program, mapset, or partitionset, CICS® dynamically creates a definition, and installs and catalogs it, as appropriate. An implicit or explicit load occurs when:

Autoinstall model definitions

Like autoinstall for terminals, program autoinstall uses model definitions, together with a user-replaceable control program, to create explicit definitions for resources that need to be autoinstalled. The purpose of a model is to provide CICS with a definition that can be used for all programs with the same properties. CICS calls the autoinstall control program with a parameter list that includes the name of a CICS-supplied, default model definition appropriate to the program type (program, mapset, or partitionset). Your autoinstall control program can accept the default model, or specify another (any installed program definition can be used as a model). It can also specify explicitly any properties that are unique to a program, thus overriding those specified on the model definition. It can specify that a local or a remote definition should be installed.

On return from the control program, CICS creates a resource definition from the model and properties returned in the parameter list.

Start of changeFor CICS programs, mapsets, or partitionsets (that is, for any objects that begin with the letters "DFH"), CICS uses the default model definitions, but does not call the user-replaceable autoinstall control program. If you have your own autoinstall control program, you cannot use it to change the resource definitions for objects that begin with the letters "DFH".End of change

Autoinstalling programs invoked by EXEC CICS LINK commands

Distributed program link (DPL) requests can be dynamically routed. (For information about the dynamic routing of DPL requests, see the CICS Intercommunication Guide.) This section describes the relationship between the autoinstall control program and the dynamic routing program.

When the autoinstall control program is invoked because there is no installed definition of a program named on an EXEC CICS LINK command, it can install:

A local definition of the server program
CICS runs the server program on the local region.
A definition that specifies REMOTESYSTEM(remote_region) and DYNAMIC(NO)
CICS ships the LINK request to the remote region.
A definition that specifies DYNAMIC(YES)
CICS invokes the dynamic routing program to route the LINK request.
Note:
The DYNAMIC attribute takes precedence over the REMOTESYSTEM attribute. Thus, a definition that specifies both REMOTESYSTEM(remote_region) and DYNAMIC(YES) defines the program as dynamic, rather than as residing on a particular remote region. (In this case, the REMOTESYSTEM attribute names the default server region passed to the dynamic routing program.)
No definition of the server program
CICS invokes the dynamic routing program to route the LINK request.
Note:
This assumes that the autoinstall control program chooses not to install a definition. If no definition is installed because autoinstall fails, the dynamic routing program is not invoked.

Autoinstall processing of mapsets

Table 29 shows the differences in mapset processing between CICS regions with program autoinstall active and inactive.

Table 29. Differences in mapset processing between autoinstall and non-autoinstall
Program autoinstall INACTIVE Program autoinstall ACTIVE
CSD definition is required.
CICS attempts to load a referenced mapset with a suffix. If this fails, CICS tries an unsuffixed version. If that is unsuccessful, abend APCT is issued.
CSD definition is not required. Using autoinstall, CICS attempts to load the referenced suffixed mapset or partitionset, then the unsuffixed one. (In each case, a definition is autoinstalled.) The transaction requesting the resource abends only if no version of the resource exists in the library, either suffixed or unsuffixed.

If the suffixed mapset was not found in the library, the definition is marked ‘not loadable’.

System autoinstall

Some programs are autoinstalled automatically (if they have not been statically defined) by the CICS system autoinstall function, which does not require model definitions or the support of the autoinstall control program. Programs in this category include:

Note:
PLTPI programs that are defined after DFHDELIM, and PLTSD programs that are defined before DFHDELIM, are treated like any other user programs--they are eligible for program autoinstall.

Related concepts
Benefits of autoinstalling programs
Related tasks
Rewriting user-replaceable programs
Assembling and link-editing user-replaceable programs
Related reference
Requirements for program autoinstall
The autoinstall control program at INSTALL
The sample autoinstall control program for programs, DFHPGADX
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