Configuring compiler defaults

When you compile an application with IBM® Open XL C/C++, the compiler uses default settings.

The default settings are determined in a number of ways:

Internally defined settings. These settings are predefined by the compiler and you cannot change them.
Settings defined by system environment variables. Certain environment variables are required by the compiler; others are optional. You might have already set some of the basic environment variables during the installation process. For more compiler installation information, see the IBM Open XL C/C++ Installation Guide. Setting environment variables provides a complete list of the required and optional environment variables you can set or reset after installing the compiler, including those used for parallel processing.