VTAM configuration

For FEPI to communicate with the network, some information must be defined to VTAM®. This is described here. For information about configuring VTAM, see the VTAM Network Implementation Guide and the VTAM Resource Definition Reference.

Defining FEPI nodes to VTAM

Each FEPI node (simulated secondary LU terminal) must have a VTAM application minor node definition. The name of this minor node must be the same as the node name specified on the FEPI INSTALL NODELIST command.

For example, the FEPI node called ‘FEPI0001’ would require the following application minor node definition in VTAM:

DG4FEPI1  APPL ACBNAME=FEPI0001

The important points to note are:

If you require password protection of the minor nodes, you can use the PRTCT keyword of the VTAM APPL statement to specify a password of 1-8 characters. The password must then be specified on the corresponding FEPI INSTALL NODELIST command.

VTAM application minor node definition statements are stored collectively as one or more members of an MVS™ partitioned data set (usually SYS1.VTAMLST), accessed by VTAM via the VTAMLST data-definition statement in the VTAM startup JCL. If you are defining multiple FEPI nodes, you may choose to place them all in a single member (also known as a VTAM application major node) or in several members. They may also be added to an existing VTAM application major node. How you choose to organize the VTAM definitions may depend on how your installation manages its network resources, or how you plan to manage the FEPI configuration.

Availability of network resources

For FEPI to communicate with the network using a node, both the application minor node and the defining major node must be active, and the minor node must be in a connectable condition.

If FEPI is initialized before VTAM, and is instructed to acquire this node, it retries the VTAM OPEN request several times. Similarly, if a target application is unavailable, FEPI makes another attempt at session initiation. After this, the operator will need to intervene to establish connectivity.

Selection of FEPI session parameters

When FEPI establishes a session with a back-end system, it searches the VTAM LOGON mode (logmode) table for an entry that corresponds to the simulated device type specified on the FEPI INSTALL PROPERTYSET command used to define the pool to which the node-target connection belongs. If it finds such an entry, it uses it to set the parameters for the session. Suitable mode table entries for FEPI are in the LOGON mode table ISTINCLM. Table 3 shows how entries in ISTINCLM correspond to FEPI device types.

Table 3. Relation of FEPI device-types to ISTINCLM mode table entries
DEVICE CVDA on
FEPI INSTALL PROPERTYSET
Mode table entry in ISTINCLM Session parameters
T3278M2 D4A32782 LU2 3278 model 2
T3278M3 D4A32783 LU2 3278 model 3
T3278M4 D4A32784 LU2 3278 model 4
T3278M5 D4A32785 LU2 3278 model 5
T3279M2 SNX32702 LU2 3279 model 2
T3279M3 SNX32703 LU2 3279 model 3
T3279M4 SNX32704 LU2 3279 model 4
T3279M5 SNX32705 LU2 3279 model 5
TPS55M2 SNX32702 LU2 PS/55, 24 lines
TPS55M3 SNX32703 LU2 PS/55, 32 lines
TPS55M4 SNX32703 LU2 PS/55, 43 lines
LUP IBM3600 Secondary LU P (IMS™ protocol LU 0)
Note:
The mode entries are fixed by FEPI; you cannot use any other entries.

If ISTINCLM is defined as your default LOGON mode table, no additional definitions are required, and FEPI sessions use the characteristics that these entries specify. If you have defined a different default table, which does not contain the supplied entries, or if you want to associate a different set of characteristics with the names listed above (for example, class-of-service or pacing specifications), then you must provide the required entries in a customized mode table. This must be associated with the node via the MODETAB keyword of the VTAM APPL statement used to define the node to VTAM. For example:

DG4FEPI1  APPL ACBNAME=FEPI0001,MODETAB=mode-table-name

Notes:
  1. If you choose to define your own mode table, it needs to contain only those entries that differ from the set supplied in the default mode table (for example, ISTINCLM). If VTAM cannot find a given entry in the node-specific mode table, it automatically searches the system default table for an entry of the same name.
  2. FEPI establishes the presentation space size of a terminal, based on the session parameters received in response to the session request, not on any fixed dimension implied by the device type specified for the pool (although the device type does establish a default value when a default BIND is received).
  3. An externally initiated session (one started by the primary LU or by the operator through the VARY LOGON command) can specify any entry name in the mode table. If you expect to make use of external session initiation, it is advisable to specify the DLOGMOD keyword on the APPL statement used to define the node in question. This keyword identifies the mode table entry to be used in those cases where the session initiation request did not specify session parameters. It can be specified regardless of whether the MODETAB keyword is used. For example:
    DG4FEPI1  APPL ACBNAME=FEPI0001,
                 MODETAB=mode-table-name,DLOGMOD=mode-table-entry-name
  4. If you define your own mode entries, ensure that all the parameters in an entry are appropriate. These logmode entries should be explicitly named in the APPL statements as described in note 3.

Pacing of FEPI sessions

The pacing values used for FEPI sessions should be consistent with whatever installation standards are in effect for other LU2 and SLU P sessions in the network.

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