diff --git a/xo-interpreter2/include/xo/interpreter2/interpreter2_register_primitives.hpp b/xo-interpreter2/include/xo/interpreter2/interpreter2_register_primitives.hpp
index 5d3f0fb1..b2e1063b 100644
--- a/xo-interpreter2/include/xo/interpreter2/interpreter2_register_primitives.hpp
+++ b/xo-interpreter2/include/xo/interpreter2/interpreter2_register_primitives.hpp
@@ -11,8 +11,9 @@
 namespace xo {
     namespace scm {
         /** Register primitive-factories **/
-        bool interpreter2_register_primitives(obj<xo::mm::AAllocator> gc,
-                                              StringTable * stbl,
+        bool interpreter2_register_primitives(obj<ARuntimeContext> rcx,
+                                              //xo::mm::AAllocator> gc,
+                                              //StringTable * stbl,
                                               InstallSink sink,
                                               InstallFlags flags);
     }
diff --git a/xo-interpreter2/src/interpreter2/interpreter2_register_primitives.cpp b/xo-interpreter2/src/interpreter2/interpreter2_register_primitives.cpp
index f0da9a8e..dba9337c 100644
--- a/xo-interpreter2/src/interpreter2/interpreter2_register_primitives.cpp
+++ b/xo-interpreter2/src/interpreter2/interpreter2_register_primitives.cpp
@@ -51,16 +51,22 @@ namespace xo {
         }
 
         bool
-        interpreter2_register_primitives(obj<xo::mm::AAllocator> mm,
-                                         StringTable * stbl,
+        interpreter2_register_primitives(obj<ARuntimeContext> rcx,
+                                         //obj<xo::mm::AAllocator> mm,
+                                         //StringTable * stbl,
                                          InstallSink sink,
                                          InstallFlags flags)
         {
             scope log(XO_DEBUG(true));
 
+            obj<AAllocator> mm = rcx.allocator();
+            StringTable * stbl = rcx.stringtable();
+
             bool ok = true;
 
-            ok = ok & install_aux(sink, VsmPrimitives::make_report_memory_use_pm(mm, stbl), flags);
+            ok = ok & install_aux(sink,
+                                  VsmPrimitives::make_report_memory_use_pm(mm, stbl),
+                                  flags);
 
             return ok;
         }
diff --git a/xo-numeric/include/xo/numeric/numeric_register_primitives.hpp b/xo-numeric/include/xo/numeric/numeric_register_primitives.hpp
index c4b0bd7b..5c68a51d 100644
--- a/xo-numeric/include/xo/numeric/numeric_register_primitives.hpp
+++ b/xo-numeric/include/xo/numeric/numeric_register_primitives.hpp
@@ -11,8 +11,9 @@
 namespace xo {
     namespace scm {
         /** Register primitive factories with primitive registry **/
-        bool numeric_register_primitives(obj<xo::mm::AAllocator> mm,
-                                         StringTable * stbl,
+        bool numeric_register_primitives(obj<ARuntimeContext> rcx,
+                                         //obj<xo::mm::AAllocator> mm,
+                                         //StringTable * stbl,
                                          InstallSink sink,
                                          InstallFlags flags);
     }
diff --git a/xo-numeric/src/numeric/numeric_register_primitives.cpp b/xo-numeric/src/numeric/numeric_register_primitives.cpp
index 6150df9f..08cb0fc9 100644
--- a/xo-numeric/src/numeric/numeric_register_primitives.cpp
+++ b/xo-numeric/src/numeric/numeric_register_primitives.cpp
@@ -51,10 +51,12 @@ namespace xo {
         }
 
         bool
-        numeric_register_primitives(obj<AAllocator> mm, StringTable * stbl,
+        numeric_register_primitives(obj<ARuntimeContext> rcx,
+                                    //obj<AAllocator> mm, StringTable * stbl,
                                     InstallSink sink, InstallFlags flags)
         {
-            (void)stbl;
+            obj<AAllocator> mm = rcx.allocator();
+            StringTable * stbl = rcx.stringtable();
 
             scope log(XO_DEBUG(true));
 
diff --git a/xo-procedure2/include/xo/procedure2/PrimitiveRegistry.hpp b/xo-procedure2/include/xo/procedure2/PrimitiveRegistry.hpp
index a4e24e2a..dd4e70b9 100644
--- a/xo-procedure2/include/xo/procedure2/PrimitiveRegistry.hpp
+++ b/xo-procedure2/include/xo/procedure2/PrimitiveRegistry.hpp
@@ -60,8 +60,9 @@ namespace xo {
              *  Allocates primitives using memory from mm, delivering them
              *  to InstallSink sink.
              **/
-            using InstallSource = std::function<bool (obj<AAllocator> mm,
-                                                      StringTable * stbl,
+            using InstallSource = std::function<bool (obj<ARuntimeContext> rcx,
+                                                      //obj<AAllocator> mm,
+                                                      //StringTable * stbl,
                                                       InstallSink sink,
                                                       InstallFlags flags)>;
 
@@ -76,8 +77,9 @@ namespace xo {
              *  with global strings in @p stbl.
              *  delivering each primitive to @p sink.
              **/
-            bool install_primitives(obj<AAllocator> mm,
-                                    StringTable * stbl,
+            bool install_primitives(obj<ARuntimeContext> rcx,
+                                    //obj<AAllocator> mm,
+                                    //StringTable * stbl,
                                     InstallSink sink,
                                     InstallFlags flags);
 
diff --git a/xo-procedure2/include/xo/procedure2/procedure2_register_primitives.hpp b/xo-procedure2/include/xo/procedure2/procedure2_register_primitives.hpp
index 396f645f..3b4fa61d 100644
--- a/xo-procedure2/include/xo/procedure2/procedure2_register_primitives.hpp
+++ b/xo-procedure2/include/xo/procedure2/procedure2_register_primitives.hpp
@@ -11,8 +11,9 @@
 namespace xo {
     namespace scm {
         /** Register primitive-factories **/
-        bool procedure2_register_primitives(obj<xo::mm::AAllocator> gc,
-                                            StringTable * stbl,
+        bool procedure2_register_primitives(obj<ARuntimeContext> rcx,
+                                            //obj<xo::mm::AAllocator> gc,
+                                            //StringTable * stbl,
                                             InstallSink sink,
                                             InstallFlags flags);
     }
diff --git a/xo-procedure2/src/procedure2/PrimitiveRegistry.cpp b/xo-procedure2/src/procedure2/PrimitiveRegistry.cpp
index 420a435e..ef5cb8c6 100644
--- a/xo-procedure2/src/procedure2/PrimitiveRegistry.cpp
+++ b/xo-procedure2/src/procedure2/PrimitiveRegistry.cpp
@@ -25,8 +25,9 @@ namespace xo {
         }
 
         bool
-        PrimitiveRegistry::install_primitives(obj<AAllocator> mm,
-                                              StringTable * stbl,
+        PrimitiveRegistry::install_primitives(obj<ARuntimeContext> rcx,
+                                              //obj<AAllocator> mm,
+                                              //StringTable * stbl,
                                               InstallSink sink,
                                               InstallFlags flags)
         {
@@ -41,7 +42,7 @@ namespace xo {
             for (const auto & fn : init_seq_v_) {
                 log && log("do install fn (", i+1, "/", n, ")");
 
-                ok = ok & fn(mm, stbl, sink, flags);
+                ok = ok & fn(rcx, /*mm, stbl,*/ sink, flags);
                 ++i;
             }
 
diff --git a/xo-procedure2/src/procedure2/procedure2_register_primitives.cpp b/xo-procedure2/src/procedure2/procedure2_register_primitives.cpp
index 29f3be19..7dd1513b 100644
--- a/xo-procedure2/src/procedure2/procedure2_register_primitives.cpp
+++ b/xo-procedure2/src/procedure2/procedure2_register_primitives.cpp
@@ -53,11 +53,15 @@ namespace xo {
         }
 
         bool
-        procedure2_register_primitives(obj<xo::mm::AAllocator> mm,
-                                       StringTable * stbl,
+        procedure2_register_primitives(obj<ARuntimeContext> rcx,
+                                       //obj<xo::mm::AAllocator> mm,
+                                       //StringTable * stbl,
                                        InstallSink sink,
                                        InstallFlags flags)
         {
+            obj<AAllocator> mm = rcx.allocator();
+            StringTable * stbl = rcx.stringtable();
+
             scope log(XO_DEBUG(true));
 
             bool ok = true;
diff --git a/xo-reader2/src/reader2/ParserStateMachine.cpp b/xo-reader2/src/reader2/ParserStateMachine.cpp
index 6ab2097b..16871d22 100644
--- a/xo-reader2/src/reader2/ParserStateMachine.cpp
+++ b/xo-reader2/src/reader2/ParserStateMachine.cpp
@@ -9,6 +9,7 @@
 #include "ToplevelSeqSsm.hpp"
 #include "DefineSsm.hpp"
 #include <xo/procedure2/PrimitiveRegistry.hpp>
+#include <xo/procedure2/SimpleRcx.hpp>
 #include <xo/object2/array/IPrintable_DArray.hpp>
 #include <xo/printable2/Printable.hpp>
 #include <xo/alloc2/Collector.hpp>
@@ -26,6 +27,7 @@ namespace xo {
     using xo::print::APrintable;
     using xo::reflect::TypeDescr;
     using xo::facet::FacetRegistry;
+    using xo::facet::with_facet;
 
     namespace scm {
         namespace {
@@ -46,7 +48,9 @@ namespace xo {
                 DGlobalEnv * env = DGlobalEnv::_make(mm,
                                                      global_symtab);
 
-                InstallSink sink = ([env, mm, &stringtable, &log]
+                DSimpleRcx rcx(mm, &stringtable);
+
+                InstallSink sink = ([env, rcx, &log]
                                     (std::string_view name,
                                      TypeDescr fn_td,
                                      obj<AProcedure> pm,
@@ -57,11 +61,11 @@ namespace xo {
                         obj<AGCObject> pm_gco = pm.to_facet<AGCObject>();
 
                         const DUniqueString * sym
-                            = stringtable.intern(name);
+                            = rcx.stringtable()->intern(name);
 
                         log && log("upsert", xtag("sym", std::string_view(*sym)));
 
-                        env->_upsert_value(mm,
+                        env->_upsert_value(rcx.allocator(),
                                            sym,
                                            fn_td,
                                            pm_gco);
@@ -70,8 +74,7 @@ namespace xo {
                     });
 
                 PrimitiveRegistry::instance()
-                    .install_primitives(mm,
-                                        &stringtable,
+                    .install_primitives(with_facet<ARuntimeContext>::mkobj(&rcx),
                                         sink,
                                         pm_install_flags);