Where is this code not freeing memory ?

Hi
       Let me first of all tell that this problem is not specific to a
compiler like gcc. It even comes in windows. So please dont regard the
question as off topic.

       I am posting a code using stl. I viewed the memory for program
by giving top command
eg: top -d 0.2 -p 'pid'
The pid will be printed out by the program itself.

Now coming to the question. The code is supposed to take around (200000
* 100 * 4 bytes = 76MB) .The top command at halfway point (line 41)
showed around 80MB. Until now it is correct. But after this i start
deleting elements from vector one by one. Then the code is supposed to
take lesser memory. But the top command showed still 80MB.
Why is this ?

I then googled and read in
http://www-1.ibm.com/support/docview.wss?rs=994&context=SSSHAD&dc=DB520&uid=swg21160634&loc=en_US&cs=UTF-8&lang=en
that stl "caches" memory and they gave a work around for it. I tried in
the code. Even that is not working.

Let me tell that valgrind or purify is not showing any leak in the
code. I some how need to free
from stl the memory. Is there any way ? Could any one help me ? I need
a general solution
which is applicable for all stl containers.

The code:

#include <vector>
#include <map>
#include<algorithm>
#include<unistd.h>
#include<iostream>
using namespace std;

//typedef vector <int, __malloc_alloc_template<0> > typIntVec;
//typedef map <long, typIntVec, std::less<long>,
//__malloc_alloc_template<0> > typLongIntVecMap;
typedef vector <int> typIntVec;
typedef map <long, typIntVec> typLongIntVecMap;

int main ()
{
                typLongIntVecMap tMap;

               cout<<"PID IS:"<<getpid()<<endl;
               sleep(2);

               cout<<"BEGIN EXECUTION."<<flush;

               typLongIntVecMap::iterator tMapItr;
               for (long j=1; j<200000; j++)
               {
                       typIntVec vec;

               //inserting 100 elements into the vector
                       for(int i=0; i<100; i++)
                       {
                               vec.push_back(i);
                       }

               //put the vector into the map
                       tMap[j] = vec;

            //simply putting a sleep so that we could see the increase in memory
                       if(j % 40000 == 0)
                       {
                               cout<<"."<<flush;
                               sleep(1);
                       }
               }

               cout<<endl<<"MEM IN STABLE POSITION......."<<endl;
               cout<<"NOW IT SHOULD DECREASE";
               sleep(2);
               for (long j=1; j<200000; j++)
               {
            //get back a reference to the vector inside the map
                       typIntVec& vecRef = tMap[j];

            //delete every element inside the vector
                       for(int i=0; i<100; i++)
                       {
                               typIntVec::iterator itr =
find(vecRef.begin(), vecRef.end(), i);
                               if(itr != vecRef.end())
                               {
                                       vecRef.erase(itr);
                               }
                       }

            //sleeping simple so that we could see the decrease in memory
                       if(j % 40000 == 0)
                       {
                               cout<<"."<<flush;
                               sleep(1);
                       }
               }

               cout<<endl<<"MAP WITH NO ELEMENTS IS IN MEM NOW"<<endl;
               sleep(2);
               return 0;
}