Hi,
First, I'd like to make sure that your question is about JMP and not MS Excel as mentioned in the title of this post.
Assuming that it is the former, here is a was to achieve your goal:
Create a new column that calculates the cumulative sum for each "X Value" category (see attached file for reference). Select this new column and set it up as "Label". In Graph Builder, set up your stacked bar graph as usual and select in the Bar sub-menu "Label" > By Row Value
Of note: I have included the script for the graph in the mock table attached to this message (top left section of the table).
I hope this helps
Best,
TS
Thierry R. Sornasse