'stress test' natural dialog

Hello, I want to perform a Natural-Dialog ‘stress test’ with 100 simultan pseudo users. How can I establish them and make them run paralell ?. I´m working on z/Os.
Thanks in advance

There are a number of commercial products out there, it all depends on from where you want to “drive” those pseudo-users. From z/OS or from a workstation ? Via SNA or via TCP/IP ?