diff --git a/include/cubescript/cubescript.hh b/include/cubescript/cubescript.hh
index b06a5493..21a62ce8 100644
--- a/include/cubescript/cubescript.hh
+++ b/include/cubescript/cubescript.hh
@@ -315,8 +315,31 @@ enum {
     CsLibAll    = 0b111
 };
 
+struct CsStackStateNode {
+    CsStackStateNode const *next;
+    CsIdent const *id;
+    int index;
+};
+
+struct CsStackState {
+    CsStackState(CsStackStateNode *nd = nullptr, bool gap = false);
+    CsStackState(CsStackState const &) = delete;
+    CsStackState(CsStackState &&st);
+    ~CsStackState();
+
+    CsStackState &operator=(CsStackState const &) = delete;
+    CsStackState &operator=(CsStackState &&);
+
+    CsStackStateNode const *get() const;
+    bool gap() const;
+
+private:
+    CsStackStateNode *p_node;
+    bool p_gap;
+};
+
 using CsHookCb = ostd::Function<void()>;
-using CsPanicCb = ostd::Function<void(CsString)>;
+using CsPanicCb = ostd::Function<void(CsString, CsStackState)>;
 
 struct OSTD_EXPORT CsState {
     CsMap<ostd::ConstCharRange, CsIdent *> idents;
@@ -353,10 +376,13 @@ struct OSTD_EXPORT CsState {
     CsPanicCb &get_panic_func();
 
     template<typename F>
-    bool pcall(F func, ostd::String *error) {
+    bool pcall(
+        F func, ostd::String *error = nullptr,
+        CsStackState *stack = nullptr
+    ) {
         return ipcall([](void *data) {
             (*static_cast<F *>(data))();
-        }, error, &func);
+        }, error, stack, &func);
     }
 
     void error(CsString msg);
@@ -476,7 +502,10 @@ struct OSTD_EXPORT CsState {
 
 private:
     CsIdent *add_ident(CsIdent *id);
-    bool ipcall(void (*f)(void *data), ostd::String *error, void *data);
+    bool ipcall(
+        void (*f)(void *data), ostd::String *error,
+        CsStackState *stack, void *data
+    );
 
     CsHookCb p_callhook;
     CsPanicCb p_panicfunc;
@@ -655,6 +684,27 @@ namespace util {
         }
         return ret;
     }
+
+    template<typename R>
+    inline ostd::Size print_stack(R &&writer, CsStackState const &st) {
+        ostd::Size ret = 0;
+        auto nd = st.get();
+        while (nd) {
+            auto rt = ostd::format(
+                writer,
+                ((nd->index == 1) && st.gap())
+                    ? "  ..%d) %s\n" : "  %d) %s\n",
+                nd->index, nd->id->get_name()
+            );
+            if (rt > 0) {
+                ret += ostd::Size(rt);
+            } else {
+                return ret;
+            }
+            nd = nd->next;
+        }
+        return ret;
+    }
 } /* namespace util */
 
 } /* namespace cscript */
diff --git a/src/cs_vm.cc b/src/cs_vm.cc
index e42c79a2..18b53f04 100644
--- a/src/cs_vm.cc
+++ b/src/cs_vm.cc
@@ -69,6 +69,69 @@ ostd::ConstCharRange cs_debug_line(
     return fmt;
 }
 
+CsStackState::CsStackState(CsStackStateNode *nd, bool gap):
+    p_node(nd), p_gap(gap)
+{}
+CsStackState::CsStackState(CsStackState &&st):
+    p_node(st.p_node), p_gap(st.p_gap)
+{
+    st.p_node = nullptr;
+    st.p_gap = false;
+}
+
+CsStackState::~CsStackState() {
+    delete[] p_node;
+}
+
+CsStackState &CsStackState::operator=(CsStackState &&st) {
+    p_node = st.p_node;
+    p_gap = st.p_gap;
+    st.p_node = nullptr;
+    st.p_gap = false;
+    return *this;
+}
+
+CsStackStateNode const *CsStackState::get() const {
+    return p_node;
+}
+
+bool CsStackState::gap() const {
+    return p_gap;
+}
+
+CsStackState cs_save_stack(CsState &cs) {
+    CsIvar *dalias = static_cast<CsIvar *>(cs.identmap[DbgaliasIdx]);
+    if (!dalias->get_value()) {
+        return CsStackState(nullptr, true);
+    }
+    int total = 0, depth = 0;
+    for (CsIdentLink *l = cs.p_callstack; l != &cs.noalias; l = l->next) {
+        total++;
+    }
+    CsStackStateNode *st =
+        new CsStackStateNode[ostd::min(total, dalias->get_value())];
+    CsStackStateNode *ret = st, *nd = st;
+    ++st;
+    for (CsIdentLink *l = cs.p_callstack; l != &cs.noalias; l = l->next) {
+        ++depth;
+        if (depth < dalias->get_value()) {
+            nd->id = l->id;
+            nd->index = total - depth + 1;
+            if (l->next == &cs.noalias) {
+                nd->next = nullptr;
+            } else {
+                nd->next = st;
+            }
+            nd = st++;
+        } else if (l->next == &cs.noalias) {
+            nd->id = l->id;
+            nd->index = 1;
+            nd->next = NULL;
+        }
+    }
+    return CsStackState(ret, total != dalias->get_value());
+}
+
 void cs_debug_alias(CsState &cs) {
     CsIvar *dalias = static_cast<CsIvar *>(cs.identmap[DbgaliasIdx]);
     if (!dalias->get_value()) {
diff --git a/src/cs_vm.hh b/src/cs_vm.hh
index 4e538187..c8c7c5e5 100644
--- a/src/cs_vm.hh
+++ b/src/cs_vm.hh
@@ -88,10 +88,15 @@ constexpr ostd::Size CsTypeStorageSize =
 
 struct CsErrorException {
     CsString errmsg;
+    CsStackState stack;
     CsErrorException() = delete;
     CsErrorException(CsErrorException const &) = delete;
-    CsErrorException(CsErrorException &&v): errmsg(ostd::move(v.errmsg)) {}
-    CsErrorException(CsString &&v): errmsg(ostd::move(v)) {}
+    CsErrorException(CsErrorException &&v):
+        errmsg(ostd::move(v.errmsg)), stack(ostd::move(v.stack))
+    {}
+    CsErrorException(CsString &&v, CsStackState &&st):
+        errmsg(ostd::move(v)), stack(ostd::move(st))
+    {}
 };
 
 ostd::ConstCharRange cs_debug_line(
@@ -100,6 +105,8 @@ ostd::ConstCharRange cs_debug_line(
 
 void cs_debug_alias(CsState &cs);
 
+CsStackState cs_save_stack(CsState &cs);
+
 template<typename ...A>
 void cs_debug_code(CsState &cs, ostd::ConstCharRange fmt, A &&...args) {
     if (cs.nodebug) {
diff --git a/src/cubescript.cc b/src/cubescript.cc
index b15ec1ee..81e39a46 100644
--- a/src/cubescript.cc
+++ b/src/cubescript.cc
@@ -261,7 +261,7 @@ CsState::CsState():
     noalias.argstack = nullptr;
 
     /* default panic func */
-    p_panicfunc = [this](CsString v) {
+    p_panicfunc = [this](CsString v, CsStackState) {
         get_err().writefln(
             "PANIC: unprotected error in call to CubeScript (%s)", v
         );
@@ -418,15 +418,21 @@ CsPanicCb &CsState::get_panic_func() {
     return p_panicfunc;
 }
 
-bool CsState::ipcall(void (*f)(void *data), ostd::String *error, void *data) {
+bool CsState::ipcall(
+    void (*f)(void *data), ostd::String *error,
+    CsStackState *stack, void *data
+) {
     ++protect;
     try {
         f(data);
-    } catch (CsErrorException const &v) {
+    } catch (CsErrorException &v) {
         --protect;
         if (error) {
             *error = ostd::move(v.errmsg);
         }
+        if (stack) {
+            *stack = ostd::move(v.stack);
+        }
         return false;
     } catch (...) {
         --protect;
@@ -438,10 +444,10 @@ bool CsState::ipcall(void (*f)(void *data), ostd::String *error, void *data) {
 
 void CsState::error(CsString msg) {
     if (protect) {
-        throw CsErrorException(ostd::move(msg));
+        throw CsErrorException(ostd::move(msg), cs_save_stack(*this));
     } else {
         if (p_panicfunc) {
-            p_panicfunc(ostd::move(msg));
+            p_panicfunc(ostd::move(msg), cs_save_stack(*this));
         }
         exit(EXIT_FAILURE);
     }
diff --git a/tools/repl.cc b/tools/repl.cc
index 59d8fee3..c4b15d68 100644
--- a/tools/repl.cc
+++ b/tools/repl.cc
@@ -197,6 +197,7 @@ static void do_call(CsState &cs, ostd::ConstCharRange line, bool file = false) {
     CsValue ret;
     signal(SIGINT, do_sigint);
     ostd::String err;
+    cscript::CsStackState st;
     if (!cs.pcall([&]() {
         if (file) {
             if (!cs.run_file(line, ret)) {
@@ -205,9 +206,10 @@ static void do_call(CsState &cs, ostd::ConstCharRange line, bool file = false) {
         } else {
             cs.run(line, ret);
         }
-    }, &err)) {
+    }, &err, &st)) {
         signal(SIGINT, SIG_DFL);
-        ostd::writeln("error: ", err);
+        cs.get_out().writeln("error: ", err);
+        cscript::util::print_stack(cs.get_out().iter(), st);
         return;
     }
     signal(SIGINT, SIG_DFL);