Optistruct ERROR:Not enough memory

Hello,

I'm running a NVH model using infinite element and MFOUR method, there is an error: Not enough memory. The Estimated Memory (RAM) for In-Core Solution is only 21583 MB, but the MAXIMUM MEMORY USED is 266791 MB, is this normal?

Is there any other way to reduce memory usage besides reducing the number of elements？ The following are some information and .out file, hope it helps.