Ideally, programs should be compiled with IBM Enterprise PL/I for z/OS and run with the supported run-time library (Language Environment). You can reach this ideal state gradually, by starting with a run-time migration followed by a compiler migration.
The remainder of this chapter explains when and why you might want to migrate your applications (run-time or source). It includes the following topics:
In this book, we use the term Enterprise PL/I as a general reference to:
In this book, we use the term PL/I as a general reference to:
Also, in this book, we refer to the 'old' and 'new' PL/I compilers in the course of the discussions. For the purposes of this book, the 'old' PL/I compilers refer to
while the 'new' PL/I compilers refer to
It is important to understand, from the very beginning, that the ‘old’ and ‘new’ PL/I compilers are completely different from each other. The ‘new’ PL/I compilers are written in PL/I, and do not make use of certain techniques that the ‘old’ PL/I compilers did. They are so different, in fact, that from the perspective of Language Environment they are considered different languages, each with its own signature CSECT.
In the past, migrating from an ‘old’ PL/I compiler to another ‘old’ PL/I compiler was not that difficult. With the introduction of the new Enterprise PL/I compiler the migration process may be much more complicated than before. Migrating to the ‘new’ Enterprise PL/I compiler must be a well researched, planned and executed project if you wish to have a smooth transition.