A power\-user interface that lets you specify an unbound config file, see
\fIunbound.conf\fR(5), which is read for configuration. Not all options are
relevant. For some specific options, such as adding trust anchors, special
-routines exist.
+routines exist. This function is thread-save only if a single instance of
+ub_ctx* exists in the application, If several instances exist the
+application has to ensure that ub_ctx_config is not called in parallel by
+the different instances.
.TP
.B ub_ctx_set_fwd
Set machine to forward DNS queries to, the caching resolver to use.