I asked the same question ITTVIS technical support but this topic might be interesting for the whole community as well. I use a quite big 2d array (15000*20000) in batch mode routine that suppose to use ENVIs libraries (ENVI_DOIT). ns=15000 nl=20000 D = make_array(ns,nl, /double) and then even before any processing step I get following message: % Unable to allocate memory: to make array. Not enough space So the question is that - did I reach some array's limitations and there is another way to define such an array. For a smaller array/image the program works properly