WebSphere Application Server processes contain two output streams that are accessible to native code running in the process. These streams are the stdout and stderr streams. Native code, including Java virtual machines (JVM), might write data to these process streams. In addition, JVM provided System.out and System.err streams can be configured to write their data to these streams also.
By default, the stdout and stderr streams are redirected to log files at application server startup, which contain text written to the stdout and stderr streams by native modules (.dlls, .exes, UNIX libraries, and other modules). By default, these files are stored as app_server_root/logs/server_name/native_stderr.log * and app_server_root/logs/native_stdout.log.
Related reference
Process logs settings
Searchable topic ID: ctrb_stdlogs