[plt-scheme] v299 scheme_config undeclared

I'm porting an extension from v208 to v299.  When I compile
for v299.19 I get a complaint

  scheme_config' undeclared

The code looks like

    event = scheme_make_struct_instance(
      scheme_eval(scheme_intern_symbol("struct:event"),
        scheme_get_env(scheme_config)),
      argc, argv);


The documentation still says

  The current thread's current parameterization is available as scheme_config.

Is scheme_config just missing from the scheme includes, or should I use
something other than scheme_config?

Thanks,

Ron
stanonik at cogsci.ucsd.edu