Terminal identifiers

The terminal identifier (TERMID) passed to the CICS® autoinstall function at install of a virtual terminal is determined using the following sequence:
  1. For EPI programs: From the NetName parameter of the CICS_EpiAddTerminal function, if specified by the Client EPI program.

    For the Client terminal emulator: From the /n parameter of the cicsterm command used to start the emulator, if specified by the workstation user.

  2. A name generated automatically by CICS.

    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 brevity, the name specified by the Client or the generated VTPREFIX name is 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 is 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.

Note: If the supplied name clashes with the name of a local terminal or connection, the installation 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 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.