Sense codes

In some cases, the application program might need to include sense information on the FMH-7 header or UNBIND RU that VTAM® creates as a result of the APPCCMD macroinstruction. This might be particularly true when the LU validates LU 6.2 protocols, as in the case of option sets that it is implementing or data in an FMH-5 header. VTAM provides the USER error type so that the application program can specify an appropriate sense code. When providing error data explicitly, use APPCCMD CONTROL=SEND, QUALIFY=ERROR, TYPE=USER or APPCCMD CONTROL=DEALLOC|DEALLOCQ, QUALIFY=ABNDUSER. In each of these cases, the sense data is coded on the SENSE parameter.

If the application program provides a USER error type, it must supply an appropriate sense code for the error. (For a list of these sense codes, see VTAM sense codes.) The receiver uses the content of the sense code to determine the response or actions of the sender.

Consider the results desired before specifying the sense code. Otherwise, improper processing of the macroinstruction might result.

Situations that the application program might be able to detect are indicated by the sense codes for:

REQUEST REJECT (category byte X'08')
REQUEST ERROR (category byte X'10')

The LU 6.2 application program probably should not use sense codes that indicate situations that it might not be able to detect. These situations are indicated by the sense codes for:

STATE ERROR (category byte X'20')
PATH ERROR (category byte X'80')
RH USAGE ERROR (category byte X'40')

The sense codes that an application program is most likely to use are those that deal with:

Security violations
Insufficient resources
Error logging
Errors in FMH headers (because the application program validates the FMH-5)

However, your application program might have unique needs that make other sense codes feasible. Consult the LU 6.2 architecture manuals for a complete list of sense codes.