Configuring SASL client

I'm sorry, I'm sure this is documented somewhere but I'm just not
finding it.

When a SASL server application calls
    result = sasl_server_init(NULL, "myserver");
the library reads configuration options from /usr/lib/sasl2/myserver.conf.

When a SASL client application calls
    result = sasl_client_init(NULL);
there's no program name specified, so what file does it read?

(I know that the caller can supply a getopt callback and supply custom
settings, but the particular caller that I'm interested in - OpenLDAP's
client - passes in NULL.)

Thanks.