Your job goes into USUSP state if the job is already started, or into PSUSP state if it is pending.
bstop 3421
Job <3421> is being stoppedThe preceding example suspends job 3421.
bstop sends the following signals to the job:
SIGTSTP for parallel or interactive jobs—SIGTSTP is caught by the master process and passed to all the slave processes running on other hosts.
SIGSTOP for sequential jobs—SIGSTOP cannot be caught by user programs. The SIGSTOP signal can be configured with the LSB_SIGSTOP parameter in lsf.conf.
bstop causes the job to be suspended.