Hi Kent,
Not sure which version (2.7 or 3.6) of Python you are using. But, It worked fine for me in 2.7…having the same issue in 3.6…Let us know if you get any solution to this problem.
Below is the code used in .py file
f2=open(’//DD:DDIN’,‘r’) /*DDIN - //DDIN DD DISP=SHR,DSN=AAAAAA.BBBB.CCCCC(DDDDD) in JCL */