DosEnterCritSec

Bindings:  C, MASM 

This call disables thread switching for the current process. 

 DosEnterCritSec    ( ) 
 

 rc (USHORT) - return 
    Return code descriptions are: 

    0         NO_ERROR 
    484       ERROR_CRITSEC_OVERFLOW 
 
 Remarks 

 DosEnterCritSec causes other threads in the process to block themselves 
 and give up their time slice. After a DosEnterCritSec request is made, no 
 dynamic link calls should be made until the corresponding DosExitCritSec 
 call is completed. 

 If a signal occurs, thread 1 begins execution to process the signal even 
 though another thread in the process has a DosEnterCritSec active. 
  (Thread 1 of a process is its initial thread of execution, not a thread 
 created with the DosCreateThread call.) Any processing done by thread 1 
 to satisfy the signal must not include accessing the critical resource 
 intended to be protected by the DosEnterCritSec request. 

 A count is maintained of the number of times a DosEnterCritSec request is 
 made without a corresponding DosExitCritSec. The count is incremented by 
 DosEnterCritSec and decremented by  DosExitCritSec. Normal thread 
 dispatching is not restored until the count is 0. The outstanding 
 DosEnterCritSec count is maintained in a word. If overflow occurs, the 
 count is set to the maximum value, no operation is performed, and the 
 request returns with an error. 

 A thread can also execute code without having to give up time slices to 
 other threads in its process if it requests a priority class that is 
 higher than those of the other threads. A thread's priority is examined 
 and changed with DosGetPrty and DosSetPrty.