What is the command or how to know to check amount of heap memory allocated and amount of stack memory allocated for process in 4 GB of ram under UNIX?

To check the amount of heap and stack memory allocated for a specific process in a UNIX environment, you can use the pmap command followed by the process ID (PID). For example, you can run pmap -x <PID> to display detailed memory usage, including heap and stack. Additionally, you can use the top or htop command to monitor the overall memory usage of processes in real-time. For more specific stack information, you might also consider examining /proc/<PID>/maps for memory segment details.