With dynamic filename assignment, the filename is specified in the SELECT clause as a COBOL data item:
select filename assign to dynamic data-item
where the parameters are:
In the following example, the file input.dat is created in the current directory:
... select fd-in-name assign to dynamic ws-in-file. ... working-storage section. 01 ws-in-file pic x(30). ... move "input.dat" to ws-in-file. ... open output fd-in-name.