diff --git a/extlib/benz/include/picrin.h b/extlib/benz/include/picrin.h
index 54f0c768..ca13b709 100644
--- a/extlib/benz/include/picrin.h
+++ b/extlib/benz/include/picrin.h
@@ -32,98 +32,13 @@ extern "C" {
 #include <limits.h>
 #include <stdarg.h>
 
-#include "picrin/config.h"
-
-#include "picrin/compat.h"
-#include "picrin/khash.h"
+#include "picrin/setup.h"
 
 typedef struct pic_state pic_state;
 
-typedef void *(*pic_allocf)(void *, void *, size_t);
-
 #include "picrin/type.h"
-#include "picrin/irep.h"
-#include "picrin/file.h"
-#include "picrin/read.h"
-#include "picrin/gc.h"
 
-KHASH_DECLARE(s, struct pic_string *, pic_sym *)
-
-typedef struct pic_checkpoint {
-  PIC_OBJECT_HEADER
-  struct pic_proc *in;
-  struct pic_proc *out;
-  int depth;
-  struct pic_checkpoint *prev;
-} pic_checkpoint;
-
-typedef struct {
-  int argc, retc;
-  pic_code *ip;
-  pic_value *fp;
-  struct pic_irep *irep;
-  struct pic_context *cxt;
-  int regc;
-  pic_value *regs;
-  struct pic_context *up;
-} pic_callinfo;
-
-struct pic_state {
-  pic_allocf allocf;
-  void *userdata;
-
-  pic_checkpoint *cp;
-  struct pic_cont *cc;
-  int ccnt;
-
-  pic_value *sp;
-  pic_value *stbase, *stend;
-
-  pic_callinfo *ci;
-  pic_callinfo *cibase, *ciend;
-
-  struct pic_proc **xp;
-  struct pic_proc **xpbase, **xpend;
-
-  pic_code *ip;
-
-  pic_value ptable;             /* list of ephemerons */
-
-  struct pic_lib *lib, *prev_lib;
-
-  pic_sym *sDEFINE, *sDEFINE_MACRO, *sLAMBDA, *sIF, *sBEGIN, *sSETBANG;
-  pic_sym *sQUOTE, *sQUASIQUOTE, *sUNQUOTE, *sUNQUOTE_SPLICING;
-  pic_sym *sSYNTAX_QUOTE, *sSYNTAX_QUASIQUOTE;
-  pic_sym *sSYNTAX_UNQUOTE, *sSYNTAX_UNQUOTE_SPLICING;
-  pic_sym *sDEFINE_LIBRARY, *sIMPORT, *sEXPORT, *sCOND_EXPAND;
-  pic_sym *sCONS, *sCAR, *sCDR, *sNILP, *sSYMBOLP, *sPAIRP;
-  pic_sym *sADD, *sSUB, *sMUL, *sDIV, *sEQ, *sLT, *sLE, *sGT, *sGE, *sNOT;
-
-  struct pic_lib *PICRIN_BASE;
-  struct pic_lib *PICRIN_USER;
-
-  pic_value features;
-
-  khash_t(s) oblist;            /* string to symbol */
-  int ucnt;
-  struct pic_weak *globals;
-  struct pic_weak *macros;
-  pic_value libs;
-  struct pic_list ireps;        /* chain */
-
-  pic_reader reader;
-  xFILE files[XOPEN_MAX];
-  pic_code iseq[2];             /* for pic_apply_trampoline */
-
-  bool gc_enable;
-  struct pic_heap *heap;
-  struct pic_object **arena;
-  size_t arena_size, arena_idx;
-
-  pic_value err;
-
-  char *native_stack_start;
-};
+typedef void *(*pic_allocf)(void *, void *, size_t);
 
 pic_state *pic_open(pic_allocf, void *);
 void pic_close(pic_state *);
@@ -262,6 +177,10 @@ struct pic_string *pic_str_sub(pic_state *, struct pic_string *, int, int);
 int pic_str_cmp(pic_state *, struct pic_string *, struct pic_string *);
 int pic_str_hash(pic_state *, struct pic_string *);
 
+/* extra stuff */
+
+#include "picrin/state.h"
+
 #include "picrin/blob.h"
 #include "picrin/cont.h"
 #include "picrin/data.h"
@@ -278,8 +197,6 @@ int pic_str_hash(pic_state *, struct pic_string *);
 #include "picrin/vector.h"
 #include "picrin/weak.h"
 
-/* extra stuff */
-
 void *pic_default_allocf(void *, void *, size_t);
 
 struct pic_object *pic_obj_alloc(pic_state *, size_t, enum pic_tt);
diff --git a/extlib/benz/include/picrin/setup.h b/extlib/benz/include/picrin/setup.h
new file mode 100644
index 00000000..ef10793f
--- /dev/null
+++ b/extlib/benz/include/picrin/setup.h
@@ -0,0 +1,104 @@
+/**
+ * See Copyright Notice in picrin.h
+ */
+
+#include "picrin/config.h"
+
+#ifndef PIC_DIRECT_THREADED_VM
+# if (defined(__GNUC__) || defined(__clang__)) && __STRICT_ANSI__ != 1
+#  define PIC_DIRECT_THREADED_VM 1
+# endif
+#endif
+
+#if PIC_NAN_BOXING && PIC_WORD_BOXING
+# error cannot enable both PIC_NAN_BOXING and PIC_WORD_BOXING simultaneously
+#endif
+
+#ifndef PIC_WORD_BOXING
+# define PIC_WORD_BOXING 0
+#endif
+
+#if ! PIC_WORD_BOXING
+# ifndef PIC_NAN_BOXING
+#  if __x86_64__ && (defined(__GNUC__) || defined(__clang__)) && __STRICT_ANSI__ != 1
+#   define PIC_NAN_BOXING 1
+#  endif
+# endif
+#endif
+
+#ifndef PIC_ENABLE_LIBC
+# define PIC_ENABLE_LIBC 1
+#endif
+
+#ifndef PIC_ENABLE_STDIO
+# define PIC_ENABLE_STDIO 1
+#endif
+
+#ifndef PIC_JMPBUF
+# include <setjmp.h>
+# define PIC_JMPBUF jmp_buf
+#endif
+
+#ifndef PIC_SETJMP
+# include <setjmp.h>
+# define PIC_SETJMP(pic, buf) setjmp(buf)
+#endif
+
+#ifndef PIC_LONGJMP
+# include <setjmp.h>
+# define PIC_LONGJMP(pic, buf, val) longjmp((buf), (val))
+#endif
+
+#ifndef PIC_ABORT
+# define PIC_ABORT(pic) abort()
+#endif
+
+#ifndef PIC_ARENA_SIZE
+# define PIC_ARENA_SIZE (8 * 1024)
+#endif
+
+#ifndef PIC_HEAP_PAGE_SIZE
+# define PIC_HEAP_PAGE_SIZE (4 * 1024 * 1024)
+#endif
+
+#ifndef PIC_PAGE_REQUEST_THRESHOLD
+# define PIC_PAGE_REQUEST_THRESHOLD(total) ((total) * 77 / 100)
+#endif
+
+#ifndef PIC_STACK_SIZE
+# define PIC_STACK_SIZE 2048
+#endif
+
+#ifndef PIC_RESCUE_SIZE
+# define PIC_RESCUE_SIZE 30
+#endif
+
+#ifndef PIC_SYM_POOL_SIZE
+# define PIC_SYM_POOL_SIZE (2 * 1024)
+#endif
+
+#ifndef PIC_IREP_SIZE
+# define PIC_IREP_SIZE 8
+#endif
+
+#ifndef PIC_POOL_SIZE
+# define PIC_POOL_SIZE 8
+#endif
+
+#ifndef PIC_SYMS_SIZE
+# define PIC_SYMS_SIZE 32
+#endif
+
+#ifndef PIC_ISEQ_SIZE
+# define PIC_ISEQ_SIZE 1024
+#endif
+
+#if DEBUG
+# include <stdio.h>
+# define GC_STRESS 0
+# define VM_DEBUG 1
+# define GC_DEBUG 0
+# define GC_DEBUG_DETAIL 0
+#endif
+
+#include "picrin/compat.h"
diff --git a/extlib/benz/include/picrin/state.h b/extlib/benz/include/picrin/state.h
new file mode 100644
index 00000000..59655643
--- /dev/null
+++ b/extlib/benz/include/picrin/state.h
@@ -0,0 +1,101 @@
+/**
+ * See Copyright Notice in picrin.h
+ */
+
+#ifndef PICRIN_STATE_H
+#define PICRIN_STATE_H
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+#include "picrin/khash.h"
+
+#include "picrin/irep.h"
+#include "picrin/file.h"
+#include "picrin/read.h"
+#include "picrin/gc.h"
+
+KHASH_DECLARE(s, struct pic_string *, pic_sym *)
+
+typedef struct pic_checkpoint {
+  PIC_OBJECT_HEADER
+  struct pic_proc *in;
+  struct pic_proc *out;
+  int depth;
+  struct pic_checkpoint *prev;
+} pic_checkpoint;
+
+typedef struct {
+  int argc, retc;
+  pic_code *ip;
+  pic_value *fp;
+  struct pic_irep *irep;
+  struct pic_context *cxt;
+  int regc;
+  pic_value *regs;
+  struct pic_context *up;
+} pic_callinfo;
+
+struct pic_state {
+  pic_allocf allocf;
+  void *userdata;
+
+  pic_checkpoint *cp;
+  struct pic_cont *cc;
+  int ccnt;
+
+  pic_value *sp;
+  pic_value *stbase, *stend;
+
+  pic_callinfo *ci;
+  pic_callinfo *cibase, *ciend;
+
+  struct pic_proc **xp;
+  struct pic_proc **xpbase, **xpend;
+
+  pic_code *ip;
+
+  pic_value ptable;             /* list of ephemerons */
+
+  struct pic_lib *lib, *prev_lib;
+
+  pic_sym *sDEFINE, *sDEFINE_MACRO, *sLAMBDA, *sIF, *sBEGIN, *sSETBANG;
+  pic_sym *sQUOTE, *sQUASIQUOTE, *sUNQUOTE, *sUNQUOTE_SPLICING;
+  pic_sym *sSYNTAX_QUOTE, *sSYNTAX_QUASIQUOTE;
+  pic_sym *sSYNTAX_UNQUOTE, *sSYNTAX_UNQUOTE_SPLICING;
+  pic_sym *sDEFINE_LIBRARY, *sIMPORT, *sEXPORT, *sCOND_EXPAND;
+  pic_sym *sCONS, *sCAR, *sCDR, *sNILP, *sSYMBOLP, *sPAIRP;
+  pic_sym *sADD, *sSUB, *sMUL, *sDIV, *sEQ, *sLT, *sLE, *sGT, *sGE, *sNOT;
+
+  struct pic_lib *PICRIN_BASE;
+  struct pic_lib *PICRIN_USER;
+
+  pic_value features;
+
+  khash_t(s) oblist;            /* string to symbol */
+  int ucnt;
+  struct pic_weak *globals;
+  struct pic_weak *macros;
+  pic_value libs;
+  struct pic_list ireps;        /* chain */
+
+  pic_reader reader;
+  xFILE files[XOPEN_MAX];
+  pic_code iseq[2];             /* for pic_apply_trampoline */
+
+  bool gc_enable;
+  struct pic_heap *heap;
+  struct pic_object **arena;
+  size_t arena_size, arena_idx;
+
+  pic_value err;
+
+  char *native_stack_start;
+};
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif
diff --git a/extlib/benz/include/picrin/type.h b/extlib/benz/include/picrin/type.h
index f6cda486..25bc9a4c 100644
--- a/extlib/benz/include/picrin/type.h
+++ b/extlib/benz/include/picrin/type.h
@@ -197,6 +197,7 @@ struct pic_proc;
 struct pic_port;
 struct pic_error;
 struct pic_env;
+struct pic_lib;
 
 /* set aliases to basic types */
 typedef struct pic_symbol pic_sym;