[xwiki-users] How to import the XAR file greater than 32 MB?

Hi When i try to import the XAR file of size 60MB i get below error message:- The wiki administrators have set a limit of 32.0Mb for attached files. Please make sure the size of the files you try to attach does not exceed this limit. I am not getting where to increase the size of XAR file to be imported ? i dont see any option under xwikipreferences.