diff --git a/conf/conf.h b/conf/conf.h
index e0f94b63..be46f172 100644
--- a/conf/conf.h
+++ b/conf/conf.h
@@ -35,7 +35,6 @@ struct config {
   u32 proto_default_debug;		/* Default protocol debug mask */
   u32 proto_default_mrtdump;		/* Default protocol mrtdump mask */
   u32 channel_default_debug;		/* Default channel debug mask */
-  u16 filter_vstk, filter_estk;		/* Filter stack depth */
   struct timeformat tf_route;		/* Time format for 'show route' */
   struct timeformat tf_proto;		/* Time format for 'show protocol' */
   struct timeformat tf_log;		/* Time format for the logfile */
diff --git a/filter/config.Y b/filter/config.Y
index f256aace..f9d9b0b3 100644
--- a/filter/config.Y
+++ b/filter/config.Y
@@ -317,7 +317,7 @@ CF_KEYWORDS(FUNCTION, PRINT, PRINTN, UNSET, RETURN,
 	MIN, MAX,
 	EMPTY,
 	FILTER, WHERE, EVAL, ATTRIBUTE,
-	BT_ASSERT, BT_TEST_SUITE, BT_CHECK_ASSIGN, BT_TEST_SAME, FORMAT, STACKS)
+	BT_ASSERT, BT_TEST_SUITE, BT_CHECK_ASSIGN, BT_TEST_SAME, FORMAT)
 
 %nonassoc THEN
 %nonassoc ELSE
@@ -343,12 +343,6 @@ CF_KEYWORDS(FUNCTION, PRINT, PRINTN, UNSET, RETURN,
 
 CF_GRAMMAR
 
-conf: FILTER STACKS expr expr ';' {
-  new_config->filter_vstk = $3;
-  new_config->filter_estk = $4;
- }
- ;
-
 conf: filter_def ;
 filter_def:
    FILTER symbol { $2 = cf_define_symbol($2, SYM_FILTER, filter, NULL); cf_push_scope( $2 ); }
diff --git a/filter/decl.m4 b/filter/decl.m4
index fc3808df..d0c86912 100644
--- a/filter/decl.m4
+++ b/filter/decl.m4
@@ -201,7 +201,6 @@ FID_INTERPRET_BODY()')
 #	that was needed in the former implementation.
 m4_define(LINEX, `FID_INTERPRET_EXEC()LINEX_($1)FID_INTERPRET_NEW()return $1 FID_INTERPRET_BODY()')
 m4_define(LINEX_, `do {
-  if (fstk->ecnt + 1 >= fstk->elen) runtime("Filter execution stack overflow");
   fstk->estk[fstk->ecnt].pos = 0;
   fstk->estk[fstk->ecnt].line = $1;
   fstk->estk[fstk->ecnt].ventry = fstk->vcnt;
@@ -239,7 +238,7 @@ FID_INTERPRET_BODY()')
 #	state the result and put it to the right place.
 m4_define(RESULT, `RESULT_TYPE([[$1]]) RESULT_([[$1]],[[$2]],[[$3]])')
 m4_define(RESULT_, `RESULT_VAL([[ (struct f_val) { .type = $1, .val.$2 = $3 } ]])')
-m4_define(RESULT_VAL, `FID_HIC(, [[do { res = $1; f_vcnt_check_overflow(1); fstk->vcnt++; } while (0)]],
+m4_define(RESULT_VAL, `FID_HIC(, [[do { res = $1; fstk->vcnt++; } while (0)]],
 [[return fi_constant(what, $1)]])')
 m4_define(RESULT_VOID, `RESULT_VAL([[ (struct f_val) { .type = T_VOID } ]])')
 
diff --git a/filter/f-inst.c b/filter/f-inst.c
index 0fb04ba7..9a3a22ab 100644
--- a/filter/f-inst.c
+++ b/filter/f-inst.c
@@ -1271,7 +1271,6 @@
     fstk->vcnt += sym->function->args;
 
     /* Storage for local variables */
-    f_vcnt_check_overflow(sym->function->vars);
     memset(&(fstk->vstk[fstk->vcnt]), 0, sizeof(struct f_val) * sym->function->vars);
     fstk->vcnt += sym->function->vars;
   }
diff --git a/filter/filter.c b/filter/filter.c
index d8a58d0a..20a380dc 100644
--- a/filter/filter.c
+++ b/filter/filter.c
@@ -50,28 +50,30 @@ enum f_exception {
   FE_RETURN = 0x1,
 };
 
-struct filter_exec_stack {
-  const struct f_line *line;		/* The line that is being executed */
-  uint pos;				/* Instruction index in the line */
-  uint ventry;				/* Value stack depth on entry */
-  uint vbase;				/* Where to index variable positions from */
-  enum f_exception emask;		/* Exception mask */
+
+struct filter_stack {
+  /* Value stack for execution */
+#define F_VAL_STACK_MAX	4096
+  uint vcnt;				/* Current value stack size; 0 for empty */
+  uint ecnt;				/* Current execute stack size; 0 for empty */
+
+  struct f_val vstk[F_VAL_STACK_MAX];	/* The stack itself */
+
+  /* Instruction stack for execution */
+#define F_EXEC_STACK_MAX 4096
+  struct {
+    const struct f_line *line;		/* The line that is being executed */
+    uint pos;				/* Instruction index in the line */
+    uint ventry;			/* Value stack depth on entry */
+    uint vbase;				/* Where to index variable positions from */
+    enum f_exception emask;		/* Exception mask */
+  } estk[F_EXEC_STACK_MAX];
 };
 
 /* Internal filter state, to be allocated on stack when executing filters */
 struct filter_state {
   /* Stacks needed for execution */
-  struct filter_stack {
-    /* Current filter stack depth */
-
-    /* Value stack */
-    uint vcnt, vlen;
-    struct f_val *vstk;
-
-    /* Instruction stack for execution */
-    uint ecnt, elen;
-    struct filter_exec_stack *estk;
-  } stack;
+  struct filter_stack *stack;
 
   /* The route we are processing. This may be NULL to indicate no route available. */
   struct rte **rte;
@@ -93,13 +95,10 @@ struct filter_state {
 };
 
 _Thread_local static struct filter_state filter_state;
+_Thread_local static struct filter_stack filter_stack;
 
 void (*bt_assert_hook)(int result, const struct f_line_item *assert);
 
-#define _f_stack_init(fs, px, def) ((fs).stack.px##stk = alloca(sizeof(*(fs).stack.px##stk) * ((fs).stack.px##len = (config && config->filter_##px##stk) ? config->filter_##px##stk : (def))))
-
-#define f_stack_init(fs) ( _f_stack_init(fs, v, 128), _f_stack_init(fs, e, 128) )
-
 static inline void f_cache_eattrs(struct filter_state *fs)
 {
   fs->eattrs = &((*fs->rte)->attrs->eattrs);
@@ -164,17 +163,15 @@ interpret(struct filter_state *fs, const struct f_line *line, struct f_val *val)
   ASSERT(line->args == 0);
 
   /* Initialize the filter stack */
-  struct filter_stack *fstk = &fs->stack;
+  struct filter_stack *fstk = fs->stack;
 
   fstk->vcnt = line->vars;
   memset(fstk->vstk, 0, sizeof(struct f_val) * line->vars);
 
   /* The same as with the value stack. Not resetting the stack for performance reasons. */
   fstk->ecnt = 1;
-  fstk->estk[0] = (struct filter_exec_stack) {
-    .line = line,
-    .pos = 0,
-  };
+  fstk->estk[0].line = line;
+  fstk->estk[0].pos = 0;
 
 #define curline fstk->estk[fstk->ecnt-1]
 
@@ -194,8 +191,6 @@ interpret(struct filter_state *fs, const struct f_line *line, struct f_val *val)
 #define v2 vv(1)
 #define v3 vv(2)
 
-#define f_vcnt_check_overflow(n) do { if (fstk->vcnt + n >= fstk->vlen) runtime("Filter execution stack overflow"); } while (0)
-
 #define runtime(fmt, ...) do { \
   if (!(fs->flags & FF_SILENT)) \
     log_rl(&rl_runtime_err, L_ERR "filters, line %d: " fmt, what->lineno, ##__VA_ARGS__); \
@@ -280,13 +275,12 @@ f_run(const struct filter *filter, struct rte **rte, struct linpool *tmp_pool, i
 
   /* Initialize the filter state */
   filter_state = (struct filter_state) {
+    .stack = &filter_stack,
     .rte = rte,
     .pool = tmp_pool,
     .flags = flags,
   };
 
-  f_stack_init(filter_state);
-
   LOG_BUFFER_INIT(filter_state.buf);
 
   /* Run the interpreter itself */
@@ -345,12 +339,11 @@ enum filter_return
 f_eval_rte(const struct f_line *expr, struct rte **rte, struct linpool *tmp_pool)
 {
   filter_state = (struct filter_state) {
+    .stack = &filter_stack,
     .rte = rte,
     .pool = tmp_pool,
   };
 
-  f_stack_init(filter_state);
-
   LOG_BUFFER_INIT(filter_state.buf);
 
   ASSERT(!((*rte)->flags & REF_COW));
@@ -369,11 +362,10 @@ enum filter_return
 f_eval(const struct f_line *expr, struct linpool *tmp_pool, struct f_val *pres)
 {
   filter_state = (struct filter_state) {
+    .stack = &filter_stack,
     .pool = tmp_pool,
   };
 
-  f_stack_init(filter_state);
-
   LOG_BUFFER_INIT(filter_state.buf);
 
   enum filter_return fret = interpret(&filter_state, expr, pres);
@@ -390,11 +382,10 @@ f_eval_int(const struct f_line *expr)
 {
   /* Called independently in parse-time to eval expressions */
   filter_state = (struct filter_state) {
+    .stack = &filter_stack,
     .pool = cfg_mem,
   };
 
-  f_stack_init(filter_state);
-
   struct f_val val;
 
   LOG_BUFFER_INIT(filter_state.buf);
diff --git a/test/birdtest.c b/test/birdtest.c
index ae05d1a5..3bf1fa77 100644
--- a/test/birdtest.c
+++ b/test/birdtest.c
@@ -246,7 +246,7 @@ bt_log_result(int result, u64 time, const char *fmt, va_list argptr)
   printf("%s\n", result_str);
 
   if (do_die && !result)
-    exit(1);
+    abort();
 }
 
 static u64