When you take a static dump of an NCP, VTAM® requires the name of the adjacent link station through which the dump operation is to be carried out. If you specify an SDLC link station name on the ID operand of the MODIFY DUMP command, VTAM uses that link station as the dump station. If you specify an NCP name, a choice of dump stations is possible. The following paragraphs describe the possible ways in which a dump station can be selected when the MODIFY DUMP command specifies an active NCP.

The dump station can be either a channel link station or an SDLC link station within an NCP. VTAM can select a dump station, or you can specify a dump station. Specify the dump station (DUMPSTA) in the PCCU definition statement, on the VARY ACT command, on the MODIFY DUMP command, or during NCP error recovery if VTAM asks you whether the NCP should be dumped. VTAM selects the dump station whenever there is no dump station name currently in effect from one of the above sources. VTAM selects a channel link station if one is available. If no channel link station is available, VTAM uses any available SDLC link station.

If you want to override a dump station name specified in the PCCU definition statement, you can use the DUMPSTA operand of the VARY ACT command to specify the name of another link station. This override capability can also be used to specify that VTAM should select the dump station. This is done by specifying a null value for the dump station (that is, specifying DUMPSTA without a value). If you choose not to override the PCCU definition statement value, VTAM uses that definition value to determine the link station to be used. The DUMPSTA operand of the MODIFY DUMP command can likewise be used to override a dump station name specified in the PCCU definition statement or on the VARY ACT command.

A link station chosen as a dump station must also be specified for automatic activation with the NCP, or must be already active when it is needed (with VTAM thus knowing of its connection to the NCP). The former method is recommended. If a specified dump station is not available for a dump operation resulting from a MODIFY DUMP command, the command fails. If a specified dump station is not available for a dump operation resulting from error recovery procedures for an NCP, VTAM either prompts you for a link station name or selects a link station from among those that are available.

As with the link stations specified for automatic activation with an NCP, the reconnection of cross-subarea links from one communication controller to another might require the changing of dump station specifications for those NCPs intended to run in the communication controllers.

Switched, X.25, and token-ring link stations are valid dump stations when you specify OPTION=STATIC,ACTION=STORE on the MODIFY DUMP command.

If you change the dump station specifications, avoid the WARM start option and the WARM operand of the VARY ACT command when you activate the affected NCPs.