How can I work with local arrays and threads

Hi All!

I have VS2013+Intel Parallel Studio XE 2015+TBB 4.3

My current code has many functions that has local stack allocations by exampe

void fnc() {

  int arr[1024];

   .............

}

when I started use fnc() in parallel for (it is some form of parallel execution) I got bad concurrent perfomance according to VTune analyser

I done some replacement for the code: int *arr = malloc(sizeof(int) * 1024). malloc I got versus from tbb of course. In the result I got very good concurrent execution. Really I can't understand why local stack allocation has concurrency problems. Can anyone describe the problem? Has this issue easy solution?

Thanks! Sorry for my bad english!