Using the STOPCAR file it is possible to stop VASP during the program execution. If the STOPCAR file contains the line
LSTOP = .TRUE.than VASP stops at the next ionic step. On the other hand, if the STOPCAR file contains the line
LABORT = .TRUE.VASP stops at the next electronic step, i.e. WAVECAR and CHGCAR might contain non converged results. If possible use the first option.