maxReceivedMessageSize and maxBufferSize in app.config

The currently accepted answer is incorrect. It is NOT required to set maxBufferSize and maxReceivedMessageSize on the client and the server binding. It depends!

If your request is too large (i.e., method parameters of the service operation are memory intensive) set the properties on the server-side, if the response is too large (i.e., the method return value of the service operation is memory intensive) set the values on the client-side.

For the difference between maxBufferSize and maxReceivedMessageSize see MaxBufferSize property?.

You need to do that on your binding, but you'll need to do it on both Client and Server. Something like:

<system.serviceModel>
    <bindings>
        <basicHttpBinding>
            <binding maxBufferSize="64000000" maxReceivedMessageSize="64000000" />
        </basicHttpBinding>
    </bindings>
</system.serviceModel>

If you are using a custom binding, you can set the values like this:

<customBinding>
    <binding name="x">
        <httpsTransport maxBufferSize="2147483647" maxReceivedMessageSize="2147483647" />
    </binding>
</customBinding>

You can do that in your app.config. like that:

maxReceivedMessageSize="2147483647" 

(The max value is Int32.MaxValue )

Or in Code:

WSHttpBinding binding = new WSHttpBinding();
binding.Name = "MyBinding";
binding.MaxReceivedMessageSize = Int32.MaxValue;

Note:

If your service is open to the Wide world, think about security when you increase this value.