The getrusage library function returns a structure containing a whole lot of data about the current process, including these:
long ru_ixrss; /* integral shared memory size */
long ru_idrss; /* integral unshared data size */
long ru_isrss; /* integral unshared stack size */
However, the most up-to-date linux documentation says about these 3 fields
(unmaintained) This field is currently unused on Linux
which the manual then defines as:
Not all fields are completed; unmaintained fields are set to zero by the kernel. (The unmaintained fields are provided for compatibility with other systems, and because they may one day be supported on Linux.)
See getrusage(2)