Efficient ways to tackle memory problems while creating a symmetric matrix

I have written a function which gives a required symmetric matrix with real values. The input variable to the function is indicative of the size of the matrix. I am running into memory issues when this size is very large(like when n=128, for my computer), even while initializing the array itself. The code looks something like this,

function C = circcont(n)
deltan = n;
xs = (-deltan:1:deltan)';
ys = (-deltan:1:deltan)';
xlength = length(xs);
ylength = length(ys);

Cu = zeros(ylength*xlength,ylength*xlength);
%..............................
% Manipulation of the Cu matrix
%..............................
C = Cu+Cu'-diag(diag(Cu));
end

The error I am receiving is "Error using zeros Requested 66049x66049 (32.5GB) array exceeds maximum array size preference. Creation of arrays greater than this limit may take a long time and cause MATLAB to become unresponsive."

I know that the main constraint is my computer memory. But is there a way I can make use of the property of symmetry of the matrix to store the values and thus make an efficient usage of the memory. Thanks.