Sorry. I spoke to John Siraco and he indicated that if an AUTOTASK definition has PREEMPT, MSTR will not proceed to the next AUTOTASK until the first is complete. If there is only one AUTOTASK, then CV will not be fully up and ready to process user tasks from terminals or ERUS until it completes.
If there are multiple AUTOTASKs all of which specify PREEMPT, they will indeed be single threaded.
In sysgen compiler if you get current on your SYSTEM number and DISPLAY ALL AUTOTASK, the order they display is the order they will be connected to CSA list of Startup Autotasks.
Hope this helps. The other suggestions given would also work.