Memory utilization

Hello, I'm running a workload replay on a new Installed oracle 11.2 database on SLES11.
The machine has 48GB Ram. Top shows a lot of sessions that allocating up to 1,9GB Memory
Total free Memory is only 1959300k

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
29851 orakrone  20   0 4303m 1.9g 1.9g S    0  4.1   6:37.48 oracle
29828 orakrone  20   0 4318m 1.8g 1.8g S   10  3.9   4:58.35 oracle
29838 orakrone  20   0 4312m 1.8g 1.8g S    0  3.9   6:23.95 oracle
29853 orakrone  20   0 4308m 1.8g 1.8g S    0  3.8   5:20.62 oracle
29876 orakrone  20   0 4311m 1.8g 1.8g S    0  3.8   5:20.59 oracle
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If I look at the database
SESSION                                            PID/THREAD       CURRENT SIZE       MAXIMUM SIZE
-------------------------------------------------- ---------- ------------------ ------------------
1147 - KRONE_WCMlxintel21                              30037            2.26 MB            6.23 MB