After the desired computation on a process grid has been completed, it is advisable to release the process grid via a call to BLACS_GRIDEXIT . When all computations have been completed, the program is exited with a call to BLACS_EXIT.
A typical code fragment to accomplish these steps would be
CALL BLACS_GRIDEXIT( ICTXT )
CALL BLACS_EXIT( 0 )
A detailed explanation of the BLACS calling sequences can be found in Appendix D and [54].