Installing connections to Clients

Unless you are using ECI over TCP/IP exclusively (see Using ECI over TCP/IP), you must install APPC connections to the Clients. The connections can be single- or parallel-session links.

Static APPC definitions

You can use CEDA DEFINE and INSTALL commands to create static definitions.

For information about defining APPC connections to non-System/390® systems, see Resource definition for communication with non-System/390 systems.

Autoinstalled APPC connections

The preferred method of installing APPC connections to Clients is to use autoinstall. If you use autoinstall, you must create some suitable CONNECTION and SESSIONS template definitions, if these do not already exist.

For information about autoinstall and defining templates, see your CICS® on System/390 Resource Definition Guide. For information about customizing your autoinstall user program to handle APPC connections, see your CICS on System/390 Customization Guide.

A connection is autoinstalled on CICS on System/390 when the Client initiates communication. (This could be, for example, when the end-user issues a cicscli /s=servername command to connect to the CICS on System/390 server, a cicsterm /s=servername command to start a 3270 emulator session, or when an ECI or EPI program is started on the Client.)

Using TCP/IP

TCP/IP communication between Clients and CICS on System/390 is supported in two ways:

  1. Via TCP62 and AnyNet®--see Using TCP62 and AnyNet
  2. Via ECI over TCP/IP--see Using ECI over TCP/IP.

Using TCP62 and AnyNet

Important

This section applies to:

System/390 software required

TCP/IP via TCP62 requires the AnyNet feature of VTAM®. The other System/390 software you require depends on the level of VTAM you are running. Table 42 shows the acceptable software combinations.

Table 42. System/390 software required for TCP/IP via TCP62 Each row lists an acceptable software combination.
  • VTAM Version 3 Release 4.2
  • Multi-Protocol Transport Feature of VTAM Version 3 Release 4.2
  • C/370™ Version 2 or later
  • MVS/ESA SP Version 3 Release 1.3 or later
  • TCP/IP Version 2 Release 2.1 or later
  • VTAM Version 4 Release 2
  • AnyNet Feature of VTAM Version 4 Release 2
  • C/370 Version 2 or later
  • MVS/ESA SP Version 3 Release 1.3 or later
  • TCP/IP Version 2 Release 2.1 or later
  • VTAM Version 4 Release 3
  • AnyNet Feature of VTAM Version 4 Release 3
  • Language Environment® for MVS™ Version 1 or later
  • MVS/ESA SP Version 3 Release 1.3 or later
  • TCP/IP Version 2 Release 2.1 or later
  • VTAM Version 4 Release 4 (also shipped as part of OS/390 Release 3 and above)
  • AnyNet (integrated into VTAM Version 4 Release 4)
  • Language Environment for MVS Version 1 Release 3 or later
  • MVS/ESA SP Version 4 Release 3 or later
  • TCP/IP Version 3 Release 1 or later
Enabling TCP/IP via TCP62

Enabling CICS to communicate with a Client using TCP/IP via TCP62 requires actions on z/OS, CICS, VTAM, and the Client workstation.

On z/OS

On z/OS, you must:

  1. Install a TCP major node. For example:
     ABHTCP   VBUILD TYPE=TCP,
                     CONTIMER=25,
                     DGTIMER=40,
                     DNSUFX=HURSLEY.IBM.COM,
                     EXTIMER=5,
                     IATIMER=60,
                     PORT=397,
                     TCB=10,
                     TCPIPJOB=TCPIP
      ABH1GRP  GROUP ISTATUS=ACTIVE
      ABH1LINE LINE  ISTATUS=ACTIVE
      ABH1PU   PU    ISTATUS=ACTIVE
     

    This defines the AnyNet interface between TCP/IP and VTAM. For further information about how to do this, see the Guide to SNA over TCP/IP manual, SC31-6527.

  2. Install a CDRSC major node. For example:
     AP23ACDS  VBUILD TYPE=CDRSC
     TCPCDGRP  GROUP
     IYCNT999  CDRSC ALSLIST=ABH1PU,MODETAB=MTCICS
     

    This defines the remote Client device and instructs VTAM to route any session requests through the TCP/IP Physical Unit (ALSLIST).

  3. Check that the Physical Unit (PU) for the AnyNet interface is active. If it is in a PCON2 state, check that VTAM has a STEPLIB to:
    DSN=PP.ADLE370.OS390R2.SCEERUN

    Start of changeThis library should be present by default.End of change

On CICS and VTAM

On CICS, you must:

  1. Define an APPC connection to the Client workstation. (The connection can be statically defined, or autoinstalled.)
  2. Set the TCP/IP system initialization parameter to 'YES'.
  3. Add an entry to the VTAM logon mode (LOGMODE) table for the modename specified on the SESSIONS definition. This entry specifies the class of service required for the group of sessions.
On the Client workstation

On the Client workstation, you must install TCP62 support and configure the Client initialization (INI) file.

Using ECI over TCP/IP

Important

This section applies only to CICS Transaction Server for z/OS, Version 2 Release 2 and later.

Enabling ECI over TCP/IP

Enabling ECI over TCP/IP requires actions on CICS and the Client workstation.

On CICS

On CICS, you must:

  1. Create a TCPIPSERVICE definition for ECI over TCP/IP. You can use the definition in RDO group DFH$SOT as supplied, edit it to suit your requirements, or create your own definition.

    A TCPIPSERVICE for ECI over TCP/IP requires SOCKETCLOSE(NO) to be specified. The recommended method to achieve a timeout for a task initiated through ECI over TCP/IP is to specify an RTIMOUT value on the mirror transaction. The standard mirror transaction, CPMI, is defined with profile DFHCICSA, which has RTIMOUT(NO). This means that long-running mirrors will wait indefinitely for data unless you customize the RTIMOUT value for the mirror transaction.

    The supplied TCPIPSERVICE definition specifies an attach-time security level of VERIFY and a TCP/IP port number of 1435. If you want some of your Clients to use LOCAL security and others to use VERIFY, you must create two TCPIPSERVICE definitions. The two definitions should have different security attributes and must listen on different ports. In each Client initialization file, specify that the Client should use the port for the appropriate security level.

  2. Install your TCPIPSERVICE definitions.
  3. Set the TCPIP system initialization parameter to 'YES'.
On the Client workstation

On the Client workstation, you must:

  1. Edit the Client initialization file. In the initialization file, code a server section like the following example:
    SECTION SERVER = ECICLNT     
      DESCRIPTION=TCP/IP Server
      UPPERCASESECURITY=N
      USENPI=N
      PROTOCOL=TCPIP
      NETNAME=hostname.example.com
      PORT=1435
      CONNECTTIMEOUT=0
      TCPKEEPALIVE=N
    ENDSECTION
    Notes:
    1. On the PORT option, specify the number of the TCP/IP port to be used for conversations with CICS.
    2. On the NETNAME option, specify the TCP/IP name of the CICS System/390 server--for example, winvmb.hursley.ibm.com.
  2. Optionally, uninstall TCP62 support.
  3. When starting the client, use a command line input of cicscli /s=ECICLNT, so that the ECICLNT section of the initialization file is used when the client starts.

When setting up Clients to use ECI over TCP/IP, bear the following in mind:

Enabling Ping support

ECI over TCP/IP support includes support for conversation-level and connection-level ping. These ping flows are initiated from CICS if a Client becomes unresponsive, but only if the mirror transaction is running with a profile that specifies a timeout. The default mirror does not have a timeout. To enable ping support you must use a mirror profile that specifies a timeout. If you don’t, and a Client becomes disconnected due to a connection failure, any current conversations with the Client could be suspended indefinitely.

When a timeout occurs, CICS does the following:

  1. If the Client supports conversation-level ping, CICS tries to ping a specific conversation. This attempts to confirm whether a conversation is still active on the connection.
  2. If the Client does not support conversation-level ping, or the conversation-level ping request times out, CICS tries a connection-level ping. This queries whether a connection to the Client still exists in TCP/IP.
  3. If the connection-level ping request times out, CICS uninstalls the Client from CICS. Any state associated with the Client is lost. Any suspended tasks associated with the Client are abended.

If a connection fails during an ECI extended conversation, CICS detects this when the ping timeout processing occurs. The conversation is abended.

Port sharing in a CICSplex

Port sharing, used as a method of load balancing in a CICSplex, is supported for TCP/IP-connected Clients.

When a Client is installed into CICS, the install request is routed to a particular CICS region. The sockets domain in that region allocates an ephemeral port for use with the Client during the rest of the time for which it is installed. The ephemeral port is not shared, so an affinity between the Client and the CICS region on which it is installed is established. Until the client is uninstalled or the connection fails (forcing the Client to be re-installed), all subsequent work is routed to the correct CICS region through the unshared ephemeral port.

Related tasks
Installing the DFHCLNT and DFHIPECI resource groups
Defining the CSCC and CIEO transient data queues
Installing Client virtual terminals
Defining a Client-attached printer
Setting up security
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