conn_handle
    OpenVMS usage:connection_id
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    The handle of the fully established connection.
 ios_icc
    OpenVMS usage:io_status_block
    type:         quadword (unsigned)
    access:       modify
    mechanism:    by 32-bit or 64-bit reference (Alpha and Integrity
                  servers)
    I/O status block:
                           +2                       0
    -------------------------------------------------
    |       Undefined       |   Completion status   |
    -------------------------------------------------
    | ios_icc$l_replyto_handle:  request_handle     | +4
    -------------------------------------------------
    Completion status values:
    SS$_NORMAL, SS$_EXQUOTA, SS$_INSFMEM, SS$_LINKABORT,
    SS$_LINKDISCON
 astadr
    OpenVMS usage:ast_procedure
    type:         procedure_entry_mask
    access:       call without stack unwinding
    mechanism:    by 32-bit or 64-bit linkage reference (Alpha and
                  Integrity servers)
    The AST routine to be executed when the operation completes.
 astprm
    OpenVMS usage:user_arg
    type:         quadword (unsigned) (Alpha and Integrity servers)
    access:       read only
    mechanism:    by 64-bit value (Alpha and Integrity servers)
    The parameter to be passed to the AST routine.
 reply_buf
    OpenVMS usage:byte_stream
    type:         character-coded text string
    access:       read only
    mechanism:    by 32-bit or 64-bit reference (Alpha and Integrity
                  servers)
    The 32-bit or 64-bit address (on Alpha and Integrity server
    systems) of the buffer containing the reply data to be sent.
    The length of this buffer is specified by the argument reply_len.
 reply_len
    OpenVMS usage:buffer_length
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    The length (in bytes) of the reply data to be sent over the
    connection. This value specifies the length of the buffer reply_
    buf. ICC segments larger buffers internally.
    The maximum Reply length is the smaller of the Reply buffer size
    supplied in the $ICC_RECEIVE call, or 1MB.
    IOS_ICC Argument:
 request_handle (input)
    OpenVMS usage:request_id
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    This parameter is passed through the ios_icc. The
    Request/Response handle from the received Transceive request
    is placed at offset ios_icc$l_replyto_handle of the ios_icc.