Tinkering with optimization level is unlikely to solve many problems with common block usage, unless you eventually use OpenMP or -parallel. You may find it useful to set -fp-model source so as to avoid aggressive algebraic recombinations. If your program violates the rule against communicating data both in COMMON and in arguments, -assume dummy_aliases may help.
It's more likely you have problems with uninitialized variables or subscript range violations. Try the static checking (-diag-enable sc) and run-time checking (-check) to help find and correct these.
