The way you set compile-time environment variables depends on your operating system.
In Windows, environment variables are set in the System window (to get there, double-click on Main and then on Control Panel). In the System window, click on Set to add a new item to the list of User Environment Variables. Options set in the Windows System window are in effect when you boot your computer unless you override them using a .CMD file or by specifying options on the command line.
For more information on environment variables and how they are used, refer to your system documentation.
The compiler provides several environment variables. They allow you to customize the defaults for:
The default location for compiler input and output is the current directory; the IBM-supplied default for each compile-time option is specified in Compile-time option descriptions.
Some of the compiler environment variables specify a directory path—this should not include a file name or extension. If the path is for compiler input, each individual path (except the last) must be delimited by a semicolon. If the path is for compiler output, only the path to a specific directory is allowed.