diff --git a/doc/ref_embed.xmlf b/doc/ref_embed.xmlf
index 2860d43d7..ef541ddb5 100644
--- a/doc/ref_embed.xmlf
+++ b/doc/ref_embed.xmlf
@@ -367,13 +367,6 @@
        <entry><constant>4192</constant></entry>
        <entry></entry>
       </row>
-      <row>
-       <entry><constant>SIGALTSTACK_SIZE</constant></entry>
-       <entry><type>cl_index</type></entry>
-       <entry><constant>1</constant></entry>
-       <entry>If nonzero, run C signal handler in an alternative
-       signal. A small value is automatically incremented.</entry>
-      </row>
       <row>
        <entry><constant>THREAD_INTERRUPT_SIGNAL</constant></entry>
        <entry><type>unsigned int</type></entry>
@@ -545,4 +538,4 @@
       nxml-outline-child-indent: 1
       fill-column: 79
       End:
- -->
\ No newline at end of file
+ -->
diff --git a/src/c/main.d b/src/c/main.d
index bd97c32cf..a519d6e9e 100755
--- a/src/c/main.d
+++ b/src/c/main.d
@@ -94,7 +94,6 @@ cl_fixnum ecl_option_values[ECL_OPT_LIMIT+1] = {
   128,            /* ECL_OPT_LISP_STACK_SAFETY_AREA */
   128*sizeof(cl_index)*1024, /* ECL_OPT_C_STACK_SIZE */
   4*sizeof(cl_index)*1024, /* ECL_OPT_C_STACK_SAFETY_AREA */
-  1,              /* ECL_OPT_SIGALTSTACK_SIZE */
   HEAP_SIZE_DEFAULT, /* ECL_OPT_HEAP_SIZE */
   1024*1024,      /* ECL_OPT_HEAP_SAFETY_AREA */
   0,              /* ECL_OPT_THREAD_INTERRUPT_SIGNAL */
diff --git a/src/doc/new-doc/user-guide/embedding.txi b/src/doc/new-doc/user-guide/embedding.txi
index d46ecc673..90254d664 100644
--- a/src/doc/new-doc/user-guide/embedding.txi
+++ b/src/doc/new-doc/user-guide/embedding.txi
@@ -157,7 +157,6 @@ The second set is related to the sizes of different stacks. Currently ECL uses f
 @item @code{LISP_STACK_SAFETY_AREA} @tab cl_index @tab 128 @tab  
 @item @code{C_STACK_SIZE} @tab cl_index @tab 131072 @tab Size of C stack (not exact).
 @item @code{C_STACK_SAFETY_AREA} @tab cl_index @tab 4192 @tab  
-@item @code{SIGALTSTACK_SIZE} @tab cl_index @tab 1 @tab If nonzero, run C signal handler in an alternative signal. A small value is automatically incremented.
 @item @code{THREAD_INTERRUPT_SIGNAL} @tab unsigned int @tab 0 @tab If nonzero, specify the unix signal which is used to communicate different Lisp threads.
 @end multitable
 @end float
diff --git a/src/h/external.h b/src/h/external.h
index f1e7a72ce..107e08a39 100755
--- a/src/h/external.h
+++ b/src/h/external.h
@@ -125,16 +125,9 @@ struct cl_env_struct {
         union ecl_ffi_values **ffi_values_ptrs;
 #endif
 
-        /* Alternative stack for processing signals */
-        void *altstack;
-        cl_index altstack_size;
-
         /* Floating point interrupts which are trapped */
         int trap_fpe_bits;
 
-        /* Old exception filter. Needed by windows. */
-        void *old_exception_filter;
-
         /* List of packages interned when loading a FASL but which have
          * to be explicitely created by the compiled code itself. */
         cl_object packages_to_be_created;
@@ -963,7 +956,6 @@ typedef enum {
         ECL_OPT_LISP_STACK_SAFETY_AREA,
         ECL_OPT_C_STACK_SIZE,
         ECL_OPT_C_STACK_SAFETY_AREA,
-        ECL_OPT_SIGALTSTACK_SIZE,
         ECL_OPT_HEAP_SIZE,
         ECL_OPT_HEAP_SAFETY_AREA,
         ECL_OPT_THREAD_INTERRUPT_SIGNAL,