Hi Adrian, thank you for reply. Yes, you are right, I assumed another thing. I don't understand how the pool size is related to thread's available workspace. You wrote, that pools are needed for allocating of book keeping info. In this case is book keeping info a page table (PT) or a page directory (PD)? If the pool is needed for PD/PT what is the method to count the size of the memory the process is capable to use. If the pool is not for PT/PD how does it influence on memory size the process is allowed to use. Could you please comment on dependency between the pool size and available memory of the second thread. In general, I want to share memory between threads, and I believe, that knowledge about pools, can help me. -- Best Regards, Rinat Dobrokhotov