A PIC +9(3) IS AN EDITED (Alphabetical) FIELD the value 0f 3 would be "+003"
B PIC 9(5) is a simple numeric field
you should use for A a PIC S9(3) in that case you could move A to B or B to A
"+" sign indicates that a positive sign will be used in the output to represent positive values and that a negative sign will represent negative values.