A quick, easy way is to use PDM. Put a 25 in the first option when looking at the source in a library. Then shift+F1 to repeat it. Enter the file name you are looking for (you can eve change the columns to search). Change option prompt to *NONE, and print list to “Y” It will give a report of all programs using this file.
Then repeat for each library.
There are packages out there that are designed just for this purpose