RECEIVE_ALLOCATE May Return AP_UNEXPECTED_DOS_ERROR (F011) (130386)

This article was previously published under Q130386

If an APPC application does not properly issue TP_ENDED for each matching TP_STARTED and RECEIVE_ALLOCATE call, the SNA Server client software eventually runs out of TP control blocks, causing the following error to be returned on a subsequent RECEIVE_ALLOCATE and TP_STARTED calls: When writing an invokable APPC transaction program (TP), that issues RECEIVE_ALLOCATE to accept a new conversation, each successful RECEIVE_ALLOCATE call returns with a unique transaction program id (tp_id) as well as a conversation id (conv_id). The conversation is eventually terminated by the TP or the partner TP by issuing a DEALLOCATE call. However, the program must still issue TP_ENDED to free up the tp_id as well, or a TP control block will remain in use on the SNA Server client. This may eventually cause the SNA Server client to run out of these control blocks, causing the APPC interface to return AP_UNEXPECTED_DOS_ERROR in response to a RECEIVE_ALLOCATE call.

NOTE: If the AP_UNEXPECTED_DOS_ERROR is occurring for some other reason, the SNA Server software may have encountered an error from an underlying operating system call. Internal SNA Server client traces and APPC API traces should be generated and passed to SNA Server support personnel to troubleshoot this type of problem.