function ini_set()
Sets the value of the given configuration option.
Returns the old value on success, FALSE on failure.
The configuration option will keep this new value during the script's execution,
and will be restored at the script's ending.
http://php.net/manual/en/function.ini-set.php
List of php.ini variables and their default value
http://php.net/manual/en/ini.php#ini.list
There are 2 sizes you could mean. With these default values.
post_max_size = 8M, upload_max_filesize = 2M
Suppose you want to change 'post_max_size' in 'php.ini' to something,
just as long your php script is running.
This is how to do it:
// saves the current setting in $old_size and sets to 30MegaByte
$old_size = ini_set( "post_max_size", "30M" );
// do something
// your code
// this is really not necessary, because when page execution is finished
// will be set back anyway
// restore php.ini setting
ini_set( "post_max_size", $old_size );
/halojoy