diff --git a/cont.c b/cont.c
index c17ee15807..251b943110 100644
--- a/cont.c
+++ b/cont.c
@@ -414,9 +414,6 @@ cont_save_thread(rb_context_t *cont, rb_thread_t *th)
     VM_ASSERT(th->status == THREAD_RUNNABLE);
     sth->errinfo = th->errinfo;
     sth->first_proc = th->first_proc;
-    sth->root_lep = th->root_lep;
-    sth->root_svar = th->root_svar;
-    sth->ensure_list = th->ensure_list;
 
     sth->trace_arg = th->trace_arg;
 
@@ -490,10 +487,10 @@ cont_capture(volatile int *volatile stat)
 	rb_ensure_list_t *p;
 	int size = 0;
 	rb_ensure_entry_t *entry;
-	for (p=th->ensure_list; p; p=p->next)
+	for (p=th->ec.ensure_list; p; p=p->next)
 	    size++;
 	entry = cont->ensure_array = ALLOC_N(rb_ensure_entry_t,size+1);
-	for (p=th->ensure_list; p; p=p->next) {
+	for (p=th->ec.ensure_list; p; p=p->next) {
 	    if (!p->entry.marker)
 		p->entry.marker = rb_ary_tmp_new(0); /* dummy object */
 	    *entry++ = p->entry;
@@ -548,6 +545,9 @@ cont_restore_thread(rb_context_t *cont)
 	th->ec.raised_flag = sth->ec.raised_flag;
 	th->ec.tag = sth->ec.tag;
 	th->ec.protect_tag = sth->ec.protect_tag;
+	th->ec.root_lep = sth->ec.root_lep;
+	th->ec.root_svar = sth->ec.root_svar;
+	th->ec.ensure_list = sth->ec.ensure_list;
     }
     else {
 	/* fiber */
@@ -558,9 +558,6 @@ cont_restore_thread(rb_context_t *cont)
 
     th->errinfo = sth->errinfo;
     th->first_proc = sth->first_proc;
-    th->root_lep = sth->root_lep;
-    th->root_svar = sth->root_svar;
-    th->ensure_list = sth->ensure_list;
 
     VM_ASSERT(sth->status == THREAD_RUNNABLE);
 }
@@ -1065,7 +1062,7 @@ rb_cont_call(int argc, VALUE *argv, VALUE contval)
 	    rb_raise(rb_eRuntimeError, "continuation called across fiber");
 	}
     }
-    rollback_ensure_stack(contval, th->ensure_list, cont->ensure_array);
+    rollback_ensure_stack(contval, th->ec.ensure_list, cont->ensure_array);
 
     cont->argc = argc;
     cont->value = make_passing_arg(argc, argv);
@@ -1265,8 +1262,8 @@ rb_fiber_start(void)
 	argv = (argc = cont->argc) > 1 ? RARRAY_CONST_PTR(args) : &args;
 	cont->value = Qnil;
 	th->errinfo = Qnil;
-	th->root_lep = rb_vm_proc_local_ep(cont->saved_thread.first_proc);
-	th->root_svar = Qfalse;
+	th->ec.root_lep = rb_vm_proc_local_ep(cont->saved_thread.first_proc);
+	th->ec.root_svar = Qfalse;
 	fib->status = FIBER_RUNNING;
 
 	EXEC_EVENT_HOOK(th, RUBY_EVENT_FIBER_SWITCH, th->self, 0, 0, 0, Qnil);
diff --git a/eval.c b/eval.c
index 916e88d74b..a49364ba41 100644
--- a/eval.c
+++ b/eval.c
@@ -895,8 +895,8 @@ rb_ensure(VALUE (*b_proc)(ANYARGS), VALUE data1, VALUE (*e_proc)(ANYARGS), VALUE
     ensure_list.entry.marker = 0;
     ensure_list.entry.e_proc = e_proc;
     ensure_list.entry.data2 = data2;
-    ensure_list.next = th->ensure_list;
-    th->ensure_list = &ensure_list;
+    ensure_list.next = th->ec.ensure_list;
+    th->ec.ensure_list = &ensure_list;
     TH_PUSH_TAG(th);
     if ((state = EXEC_TAG()) == TAG_NONE) {
 	result = (*b_proc) (data1);
@@ -906,7 +906,7 @@ rb_ensure(VALUE (*b_proc)(ANYARGS), VALUE data1, VALUE (*e_proc)(ANYARGS), VALUE
     if (!NIL_P(errinfo) && !RB_TYPE_P(errinfo, T_OBJECT)) {
 	th->errinfo = Qnil;
     }
-    th->ensure_list=ensure_list.next;
+    th->ec.ensure_list=ensure_list.next;
     (*ensure_list.entry.e_proc)(ensure_list.entry.data2);
     th->errinfo = errinfo;
     if (state)
diff --git a/thread.c b/thread.c
index cb88611bda..e7f6273199 100644
--- a/thread.c
+++ b/thread.c
@@ -581,8 +581,8 @@ thread_do_start(rb_thread_t *th, VALUE args)
 	rb_proc_t *proc;
 	GetProcPtr(th->first_proc, proc);
 	th->errinfo = Qnil;
-	th->root_lep = rb_vm_proc_local_ep(th->first_proc);
-	th->root_svar = Qfalse;
+	th->ec.root_lep = rb_vm_proc_local_ep(th->first_proc);
+	th->ec.root_svar = Qfalse;
 	EXEC_EVENT_HOOK(th, RUBY_EVENT_THREAD_BEGIN, th->self, 0, 0, 0, Qundef);
 	th->value = rb_vm_invoke_proc(th, proc,
 				      (int)RARRAY_LEN(args), RARRAY_CONST_PTR(args),
diff --git a/vm.c b/vm.c
index d5382125b8..2e94f72c0e 100644
--- a/vm.c
+++ b/vm.c
@@ -2407,7 +2407,7 @@ rb_thread_mark(void *ptr)
     RUBY_MARK_UNLESS_NULL(th->errinfo);
     RUBY_MARK_UNLESS_NULL(th->pending_interrupt_queue);
     RUBY_MARK_UNLESS_NULL(th->pending_interrupt_mask_stack);
-    RUBY_MARK_UNLESS_NULL(th->root_svar);
+    RUBY_MARK_UNLESS_NULL(th->ec.root_svar);
     RUBY_MARK_UNLESS_NULL(th->top_self);
     RUBY_MARK_UNLESS_NULL(th->top_wrapper);
     rb_fiber_mark_self(th->fiber);
@@ -2539,7 +2539,7 @@ th_init(rb_thread_t *th, VALUE self)
     th->status = THREAD_RUNNABLE;
     th->errinfo = Qnil;
     th->last_status = Qnil;
-    th->root_svar = Qfalse;
+    th->ec.root_svar = Qfalse;
     th->ec.local_storage_recursive_hash = Qnil;
     th->ec.local_storage_recursive_hash_for_trace = Qnil;
 #ifdef NON_SCALAR_THREAD_ID
@@ -2564,7 +2564,7 @@ ruby_thread_init(VALUE self)
 
     th->top_wrapper = 0;
     th->top_self = rb_vm_top_self();
-    th->root_svar = Qfalse;
+    th->ec.root_svar = Qfalse;
     return self;
 }
 
diff --git a/vm_core.h b/vm_core.h
index 29cb0ad73a..d58130af07 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -751,6 +751,13 @@ typedef struct rb_thread_context_struct {
     st_table *local_storage;
     VALUE local_storage_recursive_hash;
     VALUE local_storage_recursive_hash_for_trace;
+
+    /* eval env */
+    const VALUE *root_lep;
+    VALUE root_svar;
+
+    /* ensure & callcc */
+    rb_ensure_list_t *ensure_list;
 } rb_execution_context_t;
 
 typedef struct rb_thread_struct {
@@ -775,10 +782,6 @@ typedef struct rb_thread_struct {
     VALUE top_self;
     VALUE top_wrapper;
 
-    /* eval env */
-    const VALUE *root_lep;
-    VALUE root_svar;
-
     /* thread control */
     rb_nativethread_id_t thread_id;
 #ifdef NON_SCALAR_THREAD_ID
@@ -845,9 +848,6 @@ typedef struct rb_thread_struct {
     rb_fiber_t *root_fiber;
     rb_jmpbuf_t root_jmpbuf;
 
-    /* ensure & callcc */
-    rb_ensure_list_t *ensure_list;
-
     /* misc */
     enum method_missing_reason method_missing_reason: 8;
     unsigned int abort_on_exception: 1;
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index b678b02884..3a8abb345a 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -369,11 +369,11 @@ lep_svar(rb_thread_t *th, const VALUE *lep)
 {
     VALUE svar;
 
-    if (lep && (th == NULL || th->root_lep != lep)) {
+    if (lep && (th == NULL || th->ec.root_lep != lep)) {
 	svar = lep[VM_ENV_DATA_INDEX_ME_CREF];
     }
     else {
-	svar = th->root_svar;
+	svar = th->ec.root_svar;
     }
 
     VM_ASSERT(svar == Qfalse || vm_svar_valid_p(svar));
@@ -386,11 +386,11 @@ lep_svar_write(rb_thread_t *th, const VALUE *lep, const struct vm_svar *svar)
 {
     VM_ASSERT(vm_svar_valid_p((VALUE)svar));
 
-    if (lep && (th == NULL || th->root_lep != lep)) {
+    if (lep && (th == NULL || th->ec.root_lep != lep)) {
 	vm_env_write(lep, VM_ENV_DATA_INDEX_ME_CREF, (VALUE)svar);
     }
     else {
-	RB_OBJ_WRITE(th->self, &th->root_svar, svar);
+	RB_OBJ_WRITE(th->self, &th->ec.root_svar, svar);
     }
 }