All VTAM® connected terminals, intersystem communication links,
and multiregion operation links must be defined using resource definition
online (RDO). See Devices supported for details of VTAM terminals supported by RDO.
A CICS® system can communicate with terminals, sequential
devices, logical units, and other systems. The TCT defines each of the devices
in the configuration. Each TCT entry defines the optional and variable features
of the device to CICS, and specifies the optional and variable features of
CICS to be used.
A terminal can be a telecommunication device; for example,
an IBM® 3279
Color Display Station, or a subsystem such as an IBM 4700 Finance Communication
System. Terminals can be local (channel-attached) or remote (link-attached).
You can use a sequential device to simulate a CICS terminal.
You can define a card reader or punch, line printer, direct access storage
device (disk drive), or magnetic tape drive as a sequential device.
A logical unit (LU) is a port through which a user of an
SNA network gains access to the network facilities.
A
system can be, for example, another CICS system, an IBM
8815 Scanmaster, an IBM Displaywriter, or an APPC/PC. Intercommunication with
CICS systems can be:
- Between different processors (intersystem communication or ISC),
using the LUTYPE 6.1 or LUTYPE 6.2 protocols, or using an intermediate system
as an indirect link. (Intercommunication with non-CICS systems also
uses ISC.)
- Within the same processor (multiregion operation or MRO),
using interregion communication (IRC). (You can also use LUTYPE 6.2 ISC within
the same processor.)
There are three ways in which you can create TCT entries, and
install them in the TCT.
- By using resource definition online (RDO) to create resource definitions
in the CICS system definition (CSD) file. You must use RDO for VTAM-connected
terminals (local and remote) and for MRO and ISC links and sessions. See Terminal definition attributes for
more information on defining terminals using RDO.For information on migrating
your temrinal definitions to the RDO equivalent, see Migrating the TCT to the CSD file.
- By using RDO and autoinstall (for VTAM-connected terminals only).
See Autoinstalling VTAM terminals for information
about autoinstall for terminals.
- By coding DFHTCT macros, assembling them, and selecting the resulting
TCT by using the TCT operand at system initialization. This way, TCT entries
can be installed at system initialization only.

You
must use
DFHTCT macros, which are described in this section, to define:
- Logical units supporting logical device codes (even though they are VTAM
devices).
- Sequential devices attached by BSAM.
- Remote TCAM terminals.
