JavaCard OS

Hi folks!
I have some doubts about static class variables in javacard applet.

Q1: Why should I never use static class variables in java card applets or to use it very carefully ?
Q2: Why does the Static variables are stored in heap and what are the issues in using them?

Hope someone clarify my doubts. Thanks!

A1:
1 The applet instance which create one static object can't be deleted (You should set the static object to null before delete the applet instance);
2 You should make sure the static object is null or not before use it.
A2:
1 The static object is allocated by the new statement, so it is located in heap. The data memory space can be located in heap or COR/COD;
2 You can use it when applet instances use one common object.

The static class variables are very useful for sharing data to across the object instance. Even to share the data among applets or packages.