PL/I provides a number of user exits that you can use to customize the PL/I product to suit your needs.
The PL/I products supply default exits and the associated source files.
If you want the exits to perform functions that are different from those supplied by the default exits, it is recommended that you modify the supplied source files as appropriate.
At times, it is useful to be able to tailor the compiler to meet the needs of your organization. For example, you might want to suppress certain messages or alter the severity of others. You might want to perform a specific function with each compilation, such as logging statistical information about the compilation into a file. A compiler user exit handles this type of function.
With PL/I, you can write your own user exit or use the exit provided with the product, either 'as is' or modified, depending on what you want to do with it. The user exit source code provided with the product can be seen in Figure 1.
This chapter provides the following information: