The DCX$COMPRESS_INIT routine initializes the context area for
    the compression of data records.

    Format

      DCX$COMPRESS_INIT  context ,map

1  –  Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

    Longword condition value. Most utility routines return a
    condition value in R0. Condition values that this routine can
    return are listed under Condition Values Returned.

2  –  Arguments

 context

    OpenVMS usage:context
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference
    Value identifying the data stream that DCX$COMPRESS_INIT
    initializes. The context argument is the address of a longword
    containing this value. You should not modify the context value
    after DCX$COMPRESS_INIT initializes it. You can define multiple
    context arguments to identify multiple data streams that are
    processed simultaneously.

 map

    OpenVMS usage:address
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    The function created by DCX$MAKE_MAP. The map argument is the
    address of the compression/expansion function's virtual address.

    The map argument must remain at this address until data
    compression is completed and the context is deleted by means
    of a call to DCX$COMPRESS_DONE.

3  –  Description

    The DCX$COMPRESS_INIT routine initializes the context area for
    the compression of data records.

    Call the DCX$COMPRESS_INIT routine after calling the DCX$ANALYZE_
    DONE routine.

4  –  Condition Values Returned

    DCX$_INVMAP        Error; invalid map. The map argument was not
                       specified correctly, or the context area is
                       invalid.
    DCX$_NORMAL        Normal successful completion.

    This routine also returns any condition values returned by
    LIB$GET_VM and LIB$FREE_VM.