One of the partners initiates transaction processing by allocating a conversation. Its partner receives the notification of the conversation through the ATTN(FMH-5) exit and issues the RCVFMH5 to accept the conversation. (You have to receive the allocate and then deallocate the conversation if you want to reject the conversation. See Deallocating a conversation for more information.) See Allocating a conversation for detailed information about allocating a conversation.

Some functions used by LU 6.2 applications require use of the APPCCMD CONTROL=PREALLOC macroinstruction prior to sending the FMH-5. See Reserving a session for a conversation for more information.