Since Isolator works with its own stack inside it needs space for it. The minimal requirement for stack size is more than 256 Kilobytes (more, not equal).
If we look at stack trace we see only one non-Typemock line: StackExchange.Redis.SocketManager.<>c.<.cctor>b__49_0(Object context)
As we can see in the source code of SocketManager, a new Thread is created with maxStackSize 32KB. Thus it causes StackOveflowException.
We can suggest to modify the Redis code in
StackExchange.Redis/StackExchange.Redis/StackExchange/Redis/SocketManager.cs - line 145
`var dedicatedWriter = new Thread(writeAllQueues, 32 * 1024);`
`var dedicatedWriter = new Thread(writeAllQueues, 512 * 1024);`
`var dedicatedWriter = new Thread(writeAllQueues);`