diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index 88556bdd..54e30236 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -18,6 +18,19 @@
 #include <math.h>
 // TODO: #include <pthread.h>
 
+// Maximum number of args that GC will accept
+#define NUM_GC_ANS 128
+
+// Which way does the CPU grow its stack?
+#define STACK_GROWS_DOWNWARD 1
+
+// Size of the stack buffer, in bytes.
+// This is used as the first generation of the GC.
+#define STACK_SIZE 250000
+
+// Size of a "page" on the heap (the 2nd generation), in bytes.
+#define HEAP_SIZE 6000000
+
 /* Define general object type. */
 typedef void *object;
 
@@ -27,6 +40,10 @@ struct gc_thread_data_t {
   // Data needed for stack-based minor GC
   char *stack_start;
   char *stack_limit;
+TODO:
+  object gc_cont;
+  object *gc_ans; //[NUM_GC_ANS];
+  short gc_num_ans;
   // List of objects moved to heap during minor GC
   void **moveBuf;
   int moveBufLen;
@@ -142,19 +159,6 @@ void gc_wait_handshake();
 /* Show diagnostic information for the GC when program terminates */
 #define DEBUG_SHOW_DIAG 0
 
-/* Maximum number of args that GC will accept */
-#define NUM_GC_ANS 128
-
-/* Which way does the CPU grow its stack? */
-#define STACK_GROWS_DOWNWARD 1
-
-/* Size of the stack buffer, in bytes.
-   This is used as the first generation of the GC. */
-#define STACK_SIZE 250000
-
-/* Size of a "page" on the heap (the 2nd generation), in bytes. */
-#define HEAP_SIZE 6000000
-
 /* Define size of object tags */
 typedef long tag_type;
 
diff --git a/runtime.c b/runtime.c
index 2f9f75e7..3527a3a4 100644
--- a/runtime.c
+++ b/runtime.c
@@ -81,6 +81,8 @@ void Cyc_check_bounds(void *data, const char *label, int len, int index) {
 /* Global variables. */
 gc_heap *Cyc_heap;
 gc_thread_data *Cyc_thread;
+
+TODO: get rid of globals below that are not needed
 clock_t start;   /* Starting time. */
 char *bottom;    /* Bottom of tospace. */
 char *allocp;    /* Cheney allocate pointer. */
@@ -92,8 +94,11 @@ char *dhbottom; /* Bottom of data heap */
 char *dhallocp; /* Current place in data heap */
 char *dhalloc_limit; /* GC beyond this limit */ 
 char *dhalloc_end;
+
 long no_gcs = 0; /* Count the number of GC's. */
 long no_major_gcs = 0; /* Count the number of GC's. */
+
+TODO: after previous change, move these to thread data structure
 object gc_cont;   /* GC continuation closure. */
 object gc_ans[NUM_GC_ANS];    /* argument for GC continuation closure. */
 int gc_num_ans;