Problem with WebSphere 7 (WARNING: Cannot set header. Response already comm

I deployu generated standard application to the stand WAS 7. By clicking on the button in the console gets message:

W setHeader WARNING: Cannot set header. Response already committed.

I have the same problem. It seems that there is a restiction in size of the response buffer in WebSphere 7. If the response is too large, WAS 7 sends the response in chunked format. As a result, it is not possible to set the response headers at the end. Is there a possibility to set the headers at the beginning of response creation?

Thanks for help