As with any RPL-based VTAM® macroinstruction, error information for the APPCCMD macroinstruction can be returned in two stages if the macroinstruction was issued asynchronously. In such cases, VTAM can pass back information when the request is accepted and when it is completed. (Refer to z/OS Communications Server: SNA Programming for complete details. Table 1 and Table 2 illustrate feedback completion information available at the two stages for the APPCCMD macroinstruction.) The completion codes are not set in the RPL or the RPL extension until the APPCCMD macroinstruction request completes. If the macroinstruction was issued synchronously, only completion information is returned.

For an asynchronous request that was accepted initially (register 15 equals 0 at the next instruction after the macroinstruction that was issued), the completion codes are available after the completion exit is scheduled or the completion ECB is posted. (You can issue the APPCCMD CONTROL=CHECK macroinstruction to make the RPL and RPL extension available for reuse by another macroinstruction request.) For a synchronous request or for an asynchronous request that was not accepted initially, the completion codes are available when the application program gets control at the next instruction following the macroinstruction request.

Register 15 contains the RTNCD value and register 0 contains the FDB2 value following the completion of the macroinstruction for synchronous APPCCMD requests or completion of the APPCCMD CONTROL=CHECK macroinstruction for asynchronous APPCCMD requests. However, a SYNAD or LERAD user exit routine can change register 15.

SYNAD and LERAD exit routines are not given control for APPCCMD macroinstruction errors except for a few errors indicated by a general return code higher than 0. For more information on these errors, see SYNAD and LERAD.

The starting points for checking feedback from an APPCCMD macroinstruction are registers 15 and 0. VTAM cannot always set the feedback fields in the RPL and RPL extension for certain errors, but the registers always contain valid feedback codes.

Register 15 contains the general return code from VTAM. Only a few values are defined for the general return code, and it gives a quick indication of whether the macroinstruction was successful. Register 0 contains either a conditional completion return code or recovery action return code. In the case of errors, it provides more detail on the cause of the error.

If both register 15 and register 0 are 0, the APPCCMD has completed (or been accepted) without error. If register 15 is 0 but register 0 contains X'0000000B', the request completed conditionally. This may not indicate an error. The application program must check the RCPRI (RPLRCPR) and RCSEC (RPLRCSC) fields in the RPL extension to determine whether an error occurred.

An RCPRI value of 0 indicates that no error occurred. The RCSEC field contains a nonzero value that contains information about the processing of the macroinstruction. For example, a successful CNOS request can complete without error, but be negotiated by the partner LU. In such cases, RCSEC is set to X'0002' to indicate that negotiation took place.

A nonzero value for RCPRI indicates abnormal completion of an APPCCMD macroinstruction. The RCPRI and RCSEC fields contain the information needed to determine the error.

The preceding guidelines all assumed a 0 general return code in register 15. Because VTAM support of LU 6.2 is designed to intercept many errors and present them to the application program in an orderly fashion, this will be the case for most APPCCMD errors. The normal situation would be a register 15, register 0 combination of X'00000000', X'0000000B' (general return code 0, conditional completion return code X'B'), with the RCPRI and RCSEC fields in the RPL extension containing return codes that define the error.

Table 1 and Table 2 indicate when RPL and RPL extension fields are set by VTAM. (Refer to z/OS Communications Server: SNA Programming for complete details.)