Maximal response size Web API .NET Core

Why does this not work.

  public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.ConfigureKestrel(serverOptions =>
                {
                    serverOptions.Limits.MaxResponseBufferSize = 10000000L;
                }).UseStartup<Startup>();
            });
}

The buffer is still 64kB. Am I doing something wrong?