The DEFAULT clause allows the user to specify a default scope for all variables in the lexical extent of any parallel region.
DEFAULT (PRIVATE | FIRSTPRIVATE | SHARED | NONE)
default (shared | none)
Specific variables can be exempted from the default using the PRIVATE, SHARED, FIRSTPRIVATE, LASTPRIVATE, and REDUCTION clauses.
The C/C++ OpenMP specification does not include private or firstprivate as a possible default. However, actual implementations may provide this option.
Using NONE as a default requires that the programmer explicitly scope all variables.
Only one DEFAULT clause can be specified on a PARALLEL directive.