The size of thread level storage under OpenMP.

[Tobias Burnus]

Toon Moene wrote:
> I have an OpenMP enabled Fortran program that dies a quick death when 
> compiled with -fopenmp
A classical problem with OpenMP is that one runs out of stack memory. 
The current stack setting can be queried using the sh/bash using "ulimit 
-s" and using the (t)csh using "limit stacksize". Try to set it to 
"unlimited". Often systems limit the available stack memory; A soft 
limit of 8192 kbytes is a typical value under Linux.

The problem is that with -fopenmp all local variables are put on the 
stack (instead of using static memory), which means that the needed 
memory might be large as this includes all arrays which are not 
dynamically allocated (allocatable, pointer, automatic arrays). The 
variables must not use the static memory as otherwise wrong results are 
obtained if several threads access the same procedure simultaneously.

However, there are tons of other things which can go wrong ...

Tobias