INT 68 - APPC/PC - CONNECTION CONTROL - DEALLOCATE
        AH = 02h subfn 0500h
        DS:DX -> control block
Return: control block updated
SeeAlso: AH=02h/SF=0100h,AH=02h/SF=0300h

Format of control block:
Offset  Size    Description
 00h 12 BYTEs   reserved
 0Ch    WORD    0500h (verb "Deallocate" or "MC_Deallocate")
 0Eh    BYTE    1 if MC_ (mapped conversation) form of verb
                0 if basic verb
 0Fh  5 BYTEs   reserved (0)
 14h    WORD    (big-endian) primary return code (see AH=02h/SF=0100h)
 16h    DWORD   (big-endian) error code (see AH=02h/SF=0100h)
 1Ah  8 BYTEs   (big-endian) TP_ID
 22h    DWORD   (big-endian) conversation ID
 26h    BYTE    00h
 27h    BYTE    type
                00h SYNC_LEVEL
                01h FLUSH
                02h ABEND_PROC
                03h ABEND_SVC
                04h ABEND_TIMER
                05h ABEND
 28h    WORD    (MC_Deallocate only) length of error log data
 2Ah    DWORD   (MC_Deallocate only) pointer to error log data

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