jit.matrix ram issue

Hi,
i use a 3d matrix for storing video. But when the matrix is bigger than 1024 576 600 i always get the error "could not allocate matrix
". The 600 frames are 1012,5 MB and it´s possible to have 2 matrixes with this size in a patch but not one bigger than 1 GB (1024 576 610). Is this behavior normal for the matrix? I´m working on MacBook Pro 4 GB 10.7.4 in Max 6 & 5 the same issue. To verify just create a new patch with [jit.matrix vid 3 char 1024 576 610 @usedstdim 1]

matthias