We are using DB2 10.1
we have tried to stop DB2 by using db2stop... it has taken long time.. so we killed it..
after that when we try to start or stop it is giving as START or STOP command is in progress
Before db2 stop, you can list running DB2 applications by command db2 list applications and if there are running applications, you can kill them by db2 force application all or kill only specific app by db2 "force application ( <App handler id> )".
You can also try disconnect your db2 session db2 disconnect current or db2 termination, if you are connected into DB2.
Short is also command db2stop force.