@Ale, inténtalo así a ver:
Código COBOL:
WORKING-STORAGE SECTION.
01 funcion PIC X(30) value spaces.
01 precio-uni COMP-2.
01 precio-uni-bin redefines precio-uni BINARY-LONG.
01 unitario PIC 9(7)V9(2) VALUE ZEROS.
01 comando-item-precio PIC X(6) VALUE "Precio".
PROCEDURE DIVISION.
move "IFOpParamFloatSet" to funcion
move 2563.33 to unitario
move unitario to precio-uni
CALL funcion WITH STDCALL USING BY CONTENT comando-item-precio
BY VALUE precio-uni-bin
RETURNING respuesta-impresor