Please follow below steps to create a websphere thread dump for memory leak issues and debugging.
1. cd to WAS_HOME/AppServer/bin
2. Enter wsadmin.sh -username <UserName> -password <PassWord> or Only wsadmin.sh if username and password is not set.
3. Using the wsadmin command prompt, get a handle to the problem application server:
Example: wsadmin>set jvm [$AdminControl completeObjectName type=JVM,process=server1,*]
change server1 Name to your server name.
4. Execute Below Command to Generate the thread dump:
wsadmin>$AdminControl invoke $jvm dumpThreads
5. Look for an output file, in the installation root directory for the product, with a name like javacore.date.time.id.txt.