In Visual Studio the follow C code causes
HEAP CORRUPTION DETECED exception at line free(x);
Why? and how do I fix it?

LPWSTR x=(LPWSTR) malloc( TCHAR(lstrlen(storeName) * sizeof(TCHAR)));
LPCWSTR storeName = (LPCWSTR)L"xxxx"; 
wcscpy_s(x, lstrlen(storeName) * sizeof(TCHAR), storeName);
free(x);

In the debugger, I can see buffer x, after line

wcscpy_s(aStorePtr->storeName, lstrlen(storeName) * sizeof(TCHAR), storeName);

(a TCHAR buffer) is filled with ‘xxxx’
the local string value,

LPCWSTR storeName = (LPCWSTR)L"xxxx";

on the stack,
so I expect to be able to free the buffer.