is the txt file free for writing?

A CICS procedure save a txt file in a dir, similar: c:\mydir\mytxt.txt

i need to know when the file is free for editing, moving, copyng...ecc, how to?

note:
- 1) i dont know the time when the process is finished
- 2) i dont know the leght of txt file (is dinamic and the lenght change based variuos paprameter from ipnput)