The following table summarizes the communication methods that CICS on Open Systems and CICS® for Windows can use:
| Communication method | Best for: | Restrictions: |
|---|---|---|
| CICS family TCP/IP | Communicating at synchronization level 0 or 1 with TXSeries for Multiplatforms, IBM® CICS Transaction Gateway, and RPC-only regions across TCP/IP | Distributed Transaction Processing (DTP) is not supported. CICS user security must be configured with care because it is not possible to reliably authenticate (identify) the remote system. |
| IPIC support over TCP/IP | Communicating over TCP/IP at synchronization level 0 or 1 with TXSeries for Multiplatforms, CICS Transaction Server for z/OS, IBM CICS Transaction Gateway with and without SSL support | Function Shipping, Asynchronous Processing, DTP and Transaction Routing are not supported. CICS user security must be configured with care because it is not possible to reliably authenticate (identify) the remote system |
| CICS PPC TCP/IP | Communicating at synchronization level 0, 1 or 2 with other TXSeries for Multiplatforms regions | Communication across machines is supported by setting the environment variable CICS_HOSTS to the remote host names. Refer to Setting up the CICS_HOSTS environment variable for details. |
| Local SNA | Fast synchronization level 0 or 1 communication with remote LU 6.2 (APPC) systems. These connections can be used to connect to any CICS product. | A supported SNA product must be installed on the same machine as is the CICS region. |
| PPC Gateway | Synchronization level 0, 1, and 2 communication with remote LU 6.2 (APPC) systems. These connections can be used to connect to any CICS product. | When using Communications Server for AIX, Communications Server for Windows, Communications Server for Linux, and HP-IA SNAplus2, the PPC Gateway server must be installed on a machine along with a supported SNA product. |
To make the best use of the information that is given in this section, consider your own installation: the systems you currently have and their capabilities, the requirements of your users, and the requirements of the systems that you want to have
If you are planning to connect your CICS region to a non-TXSeries for Multiplatforms product, refer to Configuring CICS for TCP/IP, and Configuring CICS for SNA.
For connections using PPC-TCP/IP, CICS uses RPCs to set up intercommunication requests. If the remote CICS region is on a different system in the network, provide the information of such remote hosts through environment variable CICS_HOSTS. CICS_HOSTS should be set to the names of the machines to which a CICS region communicates using PPC-TCP/IP protocol. For information about setting the CICS_HOSTS environment variable, refer to Setting up the CICS_HOSTS environment variable.