Undesired /tmp/imageioNNNNNNNNNNNN.tmp files

Sentinel-1 Terrain Correction production graphs are creating/using <100 MB imageio tmp files.
“Use FileCache in readers to conserve memory” is not selected in S1TBX Options. This seems to be the most likely source for the files, and if so then this option is being ignored.
I would like to use memory instead of disk, since I have sufficient memory.
One solution is to mount /tmp on /dev/shm, however, it would be better to be able to specify the location as a setting in SNAP or S1TBX Options.