A file used within a PL/I program has a PL/I file name. A data set also has a name by which it is known to the operating system.
PL/I needs a way to recognize the data sets to which the PL/I files in your program refer, so you must provide an identification of the data set to be used, or allow PL/I to use a default identification.
You can identify the data set explicitly using either an environment variable or the TITLE option of the OPEN statement.
To use PL/I dynamic allocation, you must specify the file names by using the DSN() format for MVS data sets, or the PATH() format for HFS files.
To access HFS files from z/OS UNIX program using PL/I dynamic allocation, you can specify the HFS filename by using one of the following methods: