How do I Use the Exception mechanism to distinguish between normal program failures, and Resource Failures

enum{
    EXCEPT_MEMORY=1000,
    EXCEPT_NO_SUCH_ACCOUNT=2000,
    EXCEPT_SESSION_TIMED_OUT=3000,
    EXCEP_BAD_PASSWORD=4000;
};

int SomeFunction(){
    if(AllocFails())throw(EXCEPT_MEMORY);
    if(!GetSession())throw(EXCEPT_SESSION_TIMED_OUT);
    if(!FindAccount())throw(EXCEPT_NO_SUCH_ACCOUNT);
    if(!CheckPassword())throw(EXCEP_BAD_PASSWORD);
    .
    .
    .
    // Do the deed, which may cause more exceptions
    .
    .
    .
    return iResult;
}
int AnotherFunction(){
    int Result;
    try{
        return SomeFunction();
    }
    catch(EXCEPT_SESSION_TIMED_OUT){
        SendErrorPage(ID_SESSION_TIMED_OUT);
        return FALSE;
    }
    catch(EXCEPT_NO_SUCH_ACCOUNT){
        SendErrorPage(ID_BAD_LOGONDATA);
        return BAD_RESULT;
    }
    catch(EXCEP_BAD_PASSWORD){
        SendErrorPage(ID_BAD_LOGONDATA);
        return BAD_RESULT;
    }
}
int BaseFunction(){
    int Result;
    try{
        Result=AnotherFunction();
        return Result;
    }
    catch(EXCEPT_MEMORY){
        SendErrorPage(ID_PAGE_BUSY_TRY_LATER);//Never Returns
    }
    catch(...){
        SendErrorPage(ID_TRY_AGAIN_CONTACT_ADMIN);//Never Returns
    }
}