Configuration parameters for image swapping.

You can specify the maximum size of live data by setting maximum_live in words. If the size of live data in heap exceeds maximum_live, then Camlimages library tries to escape part of image buffer into "swap" files. If swapped data are required, they are read back into memory. This swapping is automatically done by the camlimages library. If maximum_live is 0, image swapping is disabled.

Swapped images are separated into block shaped "partitions". maximum_block_size is a maximum size of each partition, also in words. This parameter may affect the swapping performance. There is no theory (yet) how we should specify it. The author of the library propose to have (!maximum_live / 10). If it is larger, each swapping becomes slower. If smaller, more swappings will occur. Too large and too small maximum_block_size, both may make the program slower.

If you use image swapping, you need to explicitly call destroy function of each image format (Rgb24.destroy, image#destroy, etc...) to free the memory and swap files of the needless images.

The defaults are both 0. (i.e. swapping is disabled )