Is the stack size of iPhone fixed?

Question

When I am trying to adjust of stack size of threads:

- (void)testStack:(NSInteger)n {
    NSThread *thread = [[NSThread alloc]initWithTarget:self selector:@s         


        

Answer 1

The stack size is bounded on the device, and in most cases cannot exceed 1MB for the main thread on iPhone OS, nor can it be shrunk.

The minimum allowed stack size for secondary threads is 16 KB and the stack size must be a multiple of 4 KB. The space for this memory is set aside in your process space at thread creation time, but the actual pages associated with that memory are not created until they are needed.

Answer 2

Actually you can set it. I am not sure if this changed with iOS 10, but on iOS 10.2.1 this does work. The only limitation is that the stack size has to be a multiple of 4kb.

pthread_attr_t tattr;
int ret = pthread_attr_init ( &tattr ) ;
size_t size;
ret = pthread_attr_getstacksize(&tattr, &size);
printf ( "Get: ret=%d,size=%zu\n" , ret , size ) ;

size = 4096 * 512 ;
ret = pthread_attr_setstacksize(&tattr, size);
int ret2 = pthread_attr_getstacksize(&tattr, &size);
printf ( "Set & Get: ret=%d ret2=%d,size=%zu\n" , ret , ret2 , size ) ;