STK_ALT           627 regexec.c        stk->type = STK_ALT;\
STK_ALT           667 regexec.c      #define STACK_PUSH_ALT(pat,s,sprev,keep)     STACK_PUSH(STK_ALT,pat,s,sprev,keep)
STK_ALT          1607 regexec.c        STACK_PUSH_ENSURED(STK_ALT, (UChar* )FinishCode);  /* bottom stack */