You can access HFS files from a batch program by specifying the HFS file name in the DD statement or in the TITLE option of the OPEN statement.
For example, to access the HFS file /u/USER/sample.txt via the DD HFS, you would code the DD statement as follows:
//HFS DD PATH='/u/USER/sample.txt',PATHOPTS=ORDONLY,DSNTYPE=HFS
To access the same file by using the TITLE option of the OPEN statement, you would code:
OPEN FILE(HFS) TITLE('//u/USER/sample.txt');
Note the two forward slashes in the TITLE option: the first indicates that what follows is a file name (rather than a DD name), and the second is the start of the fully qualified HFS file name (and fully qualified names have to be used when HFS files are referenced under batch since there is no "current directory" that could be used to complete a file specification).
This is the order in which PL/I decides how to treat HFS files under batch: