When a member is Dynamic Calc, Essbase does not calculate the value for that member until a user requests it. After the user views it, Essbase does not store the value for that member. If you tag a member as Dynamic Calc and Store, Essbase performs the same operation as for a Dynamic Calc member but then stores the data value. See Dynamically Calculating Data Values.
Essbase automatically tags members of attribute dimensions as Dynamic Calc. You cannot change this setting.