Keyur Kanade
Ansys Employee
Design Modeler >Units >Large model support > On 

It has to be defined before the first geometric operation. Once the first geometry operation is made, the option become grey and can't be changed.  The only solution is to open another DM, use the feature "Large Model Support"  and import the previous agdb. (please note that previous operation made in the .agdb won't be accessible)