For POST request with a lot of input variables, you may want to increase the max_input_vars directive. (default = 1000)
How many input variables may be accepted (limit is applied to $_GET, $_POST and $_COOKIE superglobal separately). Use of this directive mitigates the possibility of denial of service attacks which use hash > collisions. If there are more input variables than specified by this directive, an E_WARNING is issued, and further input variables are truncated from the request.
php_value max_input_vars 1000
Please note, ini_set have no effect.