Take a look at these threads.
Do you really have to save DBL data?? could you change it to I32 or smaller?
If you have a sub-vi that consumes a lot of memory, you could try request deallocation vi:
Deallocates unused memory after the VI that contains this function runs. When a top-level VI calls a subVI, LabVIEW allocates a data space of memory in which that subVI runs. When the subVI finishes running, LabVIEW does not deallocate the data space until the top-level VI finishes running or until the entire application stops, which can result in out-of-memory conditions and degradation of performance. Place the Request Deallocation function in the subVI you want to deallocate memory for. When you set the flag Boolean input to TRUE, LabVIEW reduces memory usage by deallocating the data space for the subVI.