Filter
Top Products
TERMIDs generated by CICS for Client terminals consist of a 1-character prefix
and a 3-character suffix. The default prefix is '\', but you can specify a different
prefix using the VTPREFIX system initialization parameter. The suffix can have
the values 'AAA' through '999'. That is, each character in the suffix can have the
value 'A' through 'Z' or '0' through '9'. The first suffix generated by CICS has the
value 'AAA'. This is followed by 'AAB', 'AAC', ... 'AAZ', 'AA0', 'AA1', and so on,
up to '999'.
Each time a Client virtual terminal is autoinstalled, CICS generates a
3-character suffix that it has not recorded as being in use.
Note: By specifying a prefix, you can ensure that the TERMIDs of Client
terminals autoinstalled on this system are unique in your transaction
routing network. This prevents the conflicts that could occur if two or
more regions ship definitions of virtual terminals to the same
application-owning region (AOR).
For details of the VTPREFIX system initialization parameter, see the CICS System
Definition Guide.
For brevity, we shall refer to the name specified by the Client or the
CICS-generated “VTPREFIX” name as the supplied name. The Client always knows
the virtual terminal by the supplied name. However, your autoinstall control program
can allocate an alias, by which the virtual terminal will be known to CICS.
If the CICS autoinstall function detects that the supplied name clashes with the
name of a remote terminal or connection already installed on this region, it
generates an alias TERMID. CICS generates alias TERMIDs for virtual terminals in
the same way as it generates aliases for shipped terminals—see “CICS-generated
aliases” on page 560.
Note: If the supplied name clashes with the name of a local terminal or connection,
the install of the virtual terminal is rejected, and the autoinstall control
program is not invoked.
The autoinstall control program is invoked once for each virtual terminal definition to
be installed. When it is invoked, field INSTALL_SHIPPED_TERMID_PTR of the
communications area points to the supplied TERMID. Field
SELECTED_SHIPPED_TERMID contains either the supplied TERMID, or a
CICS-generated alias, depending on whether a clash of names has been detected.
Your control program can accept the TERMID passed in
SELECTED_SHIPPED_TERMID, change it, or reject the installation of the virtual
terminal.
Why override TERMIDs?
Why might you want to create an alias for the supplied TERMID (or, in the case of
a clash of names, to override the alias generated by CICS)? You may not need to;
it may depend on the way in which your server programs are written. By “server
programs” we mean both the transaction programs started by Client EPI programs,
and those started from the Client terminal emulator.
Overriding CICS-generated TERMIDs
If you are using CICS-generated TERMIDs (and have specified a different prefix,
reserved for virtual terminals, on each region on which Client terminals can be
installed), there should be no clash of names, either in the regions in which the
virtual terminals are installed, or when different regions ship Client definitions to the
568 Customization Guide