Controlling FEPI resources

The FEPI INQUIRE and SET functions can be carried out by a program, or by using the master terminal transaction, CEMT. You may find it useful to write some specialized operator transactions of your own.

The FEPI INQUIRE command (and its CEMT equivalent) tells you what resources are defined and their statuses. The only thing you cannot do directly is determine which nodes and targets are in a particular pool. Do this using CEMT to inquire about the connections in a particular pool:

CEMT I FECONNECTION POOL(poolname)

To do this from an application program, browse all connections and select those in the pool you want.

Here are the resource statuses of most interest:

SERVSTATUS

SERVSTATUS is used with connections, nodes, pools, and targets. It specifies the service status of the resource--that is, whether it can be used for a conversation. The service status can be set to INSERVICE to allow usage, or to OUTSERVICE to stop usage for any new conversation. Note that setting OUTSERVICE does not end any existing conversations that are using the resource; the status is GOINGOUT until the existing conversations end.

ACQSTATUS

ACQSTATUS is used with connections and nodes. It specifies the "acquire status" of the resource. For a connection, this means whether it should have a session established (bound) or ended (unbound). For a node, it means whether the VTAM® ACB for the node should be opened or closed. The acquire status can be set to ACQUIRED (a status of ACQUIRING indicates that the acquisition has not yet been completed), or to RELEASED.

Setting RELEASED does not end any existing conversations that are using the resource; the acquire status is RELEASING until the existing conversations end. However, for connections, a conversation that is unowned and in a "pending" state (see STATE) is ended immediately if the acquire state is set to RELEASED; this means that connections being used by a failed application can be recovered.

ACQUIRING and RELEASING are shown as BEING ACQUIRED and BEING RELEASED by CEMT.

Network and other problems can cause connections to become stuck in a RELEASING or ACQUIRING state, in which case the operator might need to intervene using VTAM operator commands.

If a FEPI connection remains in a RELEASING state for longer than expected, try the following:

  1. Note the node and target associated with the connection; use CEMT INQUIRE FETARGET to find the VTAM application name that the target represents.
  2. Issue the VTAM command
    D NET,E,ID=nodename
    to find out the state of network session associated with the connection.
  3. Note the session status. See the VTAM Programming manual for an explanation of the status. If no session exists and a subsequent INQUIRE of the connection status using CEMT shows the state still as BEING RELEASED, there has been a system failure; you should collect diagnostic information.
  4. If the session is in ‘session takedown processing’, you can use the VTAM command
    D NET,SESSION
    to find out what signals are needed to complete processing.
  5. If you can resolve the problem using commands on the back-end system, attempt to do so.
  6. If there is no other way to resolve the session status, you can use the VTAM command
    V NET,TERM
    to end the network procedure in progress. FEPI will then be able to complete processing.

It is not so easy to find out when an ACQUIRING state has persisted for too long. However, if you cannot determine why the session has not been established, follow the procedure described above. If no session is active for the connection, FEPI is currently waiting for the retry interval to expire. The system log should contain VTAM messages explaining why the session cannot be established. The LACQCODE option of CEMT INQUIRE FECONNECTION gives the reason code VTAM provided for the last session failure.

Also be sure to check that the node on which the connection depends is properly acquired; if not, resolve whatever problem is indicated by the LACQCODE option for the node.

Note that, under normal circumstances, after a FEPI FREE RELEASE command has been issued the session does not remain in RELEASED state, because FEPI automatically tries to reacquire the session. However, if a FEPI SET CONNECTION ACQSTATUS(RELEASED) command is issued before the FREE RELEASE, the session remains in RELEASED state.

LASTACQCODE

The INQUIRE CONNECTION or INQUIRE NODE commands can use the option LASTACQCODE (LACQCODE in CEMT), which returns the result of the last acquire request. This is the sense code from the last VTAM operation, where zero indicates success. For a full explanation of VTAM sense codes, see the appropriate VTAM manual: for nodes, this is VTAM Programming; for connections, VTAM Messages and Codes. Further information is in the SNA Formats manual.

INSTLSTATUS

INSTLSTATUS is used with connections, nodes, pools, and targets. It specifies whether the resource is installed, or is in the process of being discarded, waiting for the conversations that are using it to end.

WAITCONVNUM

WAITCONVNUM shows how many conversations are currently waiting to start using a connection or pool. If WAITCONVNUM is nonzero for significant periods of time, it might mean that you need to allocate extra resources to meet the demand. Or it might mean that applications are holding on to resources for too long.

STATE

STATE is used with connections. It shows the state of the conversation that is using a connection. See State for the values that STATE can have.

If any of the "pending" states (PENDSTSN, PENDBEGIN, PENDDATA, PENDSTART, PENDFREE, PENDRELEASE, PENDUNSOL, or PENDPASS) is shown, it indicates that the conversation is unowned, pending the event or task shown. If a "pending" state persists, it is likely that the application has failed in some way; you should consider resetting the connection by issuing a FEPI SET CONNECTION RELEASED command.

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