一、Run-time data areas

PC
▪ Each Java Virtual Machine thread has its own pc (program counter) 
register.
▪ At any point, each Java Virtual Machine thread is executing the code 
of a single method, namely the current method for that thread.
▪ If that method is not native , the pc register contains the address of 
the Java Virtual Machine instruction currently being executed.JVM Stacks
▪ Each Java Virtual Machine thread has a private Java Virtual 
Machine stack, created at the same time as the thread.
▪ A Java Virtual Machine stack stores framesHeap
▪ The Java Virtual Machine has a heap that is shared among 
all Java Virtual Machine threads.
▪ The heap is the run-time data area from which memory for 
all class instances and arrays is allocated.Method Area
▪ The Java Virtual Machine has a method area that is shared
among all Java Virtual Machine threads. 
▪ It stores per-class structuresRun-Time Constant Pool
▪ A run-time constant pool is