Both the automatic caching and the DiskCache node use the same cache directory defined using the Preferences dialog. In the Preferences, you can also set the maximum size you allow the disk cache to consume. For more information on the caching preferences, see Defining the Settings for Caching below.
Note that the cached images have unique names reflecting their point of output location in the script. This means that you can cache images from multiple nodes in the script without overwriting previously cached images.