The JCC downloads the SnapPack on first use of a particular version of a SnapPack. The downloaded SnapPack is cached locally to disk. By default, the disk cache is cleared when JCC restarts. This helps reduce disk usage, since SnapPack versions change and the list of cached SnapPacks can grow.
Setting -DDISABLE_SNAP_CACHE_DELETE=True causes the JCC to retain the existing cache after JCC process restart. This can help if a JCC is on a slow network, where SnapPack downloads are slow. The correct version of the SnapPack is still used, the cache is ignored if it has an older version. The downside is that the cache folder can grow over time. To manually clear the cache folder, stop JCC, run “jcc.sh clearcache” and then start JCC again.