When mcexec reduces a stack, mcexec stores the original RLIMIT_STACK in environment variable MCKERNEL_RLIMIT_STACK. A fix to prohibit overwrite of this time. Therefore, the value of RLIMIT_STACK of the McKernel's process is decided in the following order. (1) If environment variable MCKERNEL_RLIMIT_STACK exists; the value. (2) A value of RLIMIT_STACK in the mcexec starting.