‑Xcompactexplicitgc / ‑Xnocompactexplicitgc
These options enable or disable full compaction each time System.gc() is called.
Compaction takes place on global garbage collections if you specify -Xcompactgc or if compaction triggers are met. 
Syntax
| Setting | Action | Default | 
|---|---|---|
| -Xcompactexplicitgc | Enable compaction | yes | 
| -Xnocompactexplicitgc | Disable compaction |