MATLAB - How to force a specific variable to be stored in memory?

I have a cell array of classifiers (for example, decision trees) trainmodel = cell(1,100000). And sometimes this thing gets really big, so is there any way to tell MATLAB that if this variable is too big, just store it in the memory? Of course I can use matfile, but the thing is that if it's not too big then it would be slower. Please help me, thank you very much.

[James Tursa]

Store it in what memory? For normal variables, they are already stored in memory the instant they are created. Are you running out of memory? Or having speed/throughput issues?