zen% ulimit -s 8192 zen% perl -wle '$n=shift; $_="a" x $n; /(ab*)+/' 10080 Segmentation fault (core dumped) zen% ulimit -s 32768 zen% perl -wle '$n=shift; $_="a" x $n; /(ab*)+/' 10080 zen% perl -wle '$n=shift; $_="a" x $n; /(ab*)+/' 32766 zen% perl -wle '$n=shift; $_="a" x $n; /(ab*)+/' 32767 Complex regular subexpression recursion limit (32766) exceeded at -e line 1. zen%