You'll need to modify the database table for static pages. Currently the sp_content field is type TEXT which allows 64K of data. You probably want to change this to MEDIUMTEXT which will give you 16M of data.
If you have access to phpMyAdmin you can run the following SQL to alter the table:
PHP Formatted Code
ALTER TABLE gl_staticpage CHANGE sp_content sp_content MEDIUMTEXT;
If you don't have access to phpMyAdmin, let me know and I'll write a quick and dirty little PHP script to take care of it.