--- a/dyncallback/dyncall_callback_sparc64.s	Sat Mar 18 19:10:01 2017 +0100
+++ b/dyncallback/dyncall_callback_sparc64.s	Sun Mar 19 19:34:34 2017 +0100
@@ -39,29 +39,63 @@
 dcCallbackThunkEntry:
 
 	/* Prolog. */
-	/* Frame size of 208b comes from needing storage space for the following: */
-	/*   DCargs(sparc_req_reg_save_area:128 + spill:64 + argptr:8) + retval:8 */
+	/* Frame size of 336b comes from needing storage space for the following: */
+	/*   req_reg_save_area:128 + spill:48 + dcargs:144 + retval:8 + pad:8 */
 	/* Spill area could theoretically be only 32b, b/c cbHandler function has */
- 	/* 4 arguments, and retval doesn't need stack, but let's be conservative. */
-	save %sp, -208, %sp
+ 	/* 4 arguments, but let's be conservative. */
+	save %sp, -336, %sp
 
-	/* Spill register args. */
-	add  %fp, BIAS + 136, %l0
-	stx  %i0, [ %l0 +  0 ]          /* reg arg 0 */
-	stx  %i1, [ %l0 +  8 ]          /* reg arg 1 */
-	stx  %i2, [ %l0 + 16 ]          /* reg arg 2 */
-	stx  %i3, [ %l0 + 24 ]          /* reg arg 3 */
-	stx  %i4, [ %l0 + 32 ]          /* reg arg 4 */
-	stx  %i5, [ %l0 + 40 ]          /* reg arg 5 */
-	stx  %l0, [ %sp + BIAS + 192 ]  /* init arg_ptr */
+	/* Spill register args as dcargs is based on that (in prev frame, after */
+	/* req_reg_save_area). */
+	add  %fp, BIAS + 128, %l0
+	stx  %i0,  [ %l0 +  0 ]          /* reg arg 0 */
+	stx  %i1,  [ %l0 +  8 ]          /* reg arg 1 */
+	stx  %i2,  [ %l0 + 16 ]          /* reg arg 2 */
+	stx  %i3,  [ %l0 + 24 ]          /* reg arg 3 */
+	stx  %i4,  [ %l0 + 32 ]          /* reg arg 4 */
+	stx  %i5,  [ %l0 + 40 ]          /* reg arg 5 */
+	stx  %l0,  [ %sp + BIAS + 176 ]  /* set DCArg's arg_ptr */
+	st   %f0,  [ %sp + BIAS + 184 ]  /* store fp args in DCArgs's dreg_data */
+	st   %f1,  [ %sp + BIAS + 188 ]  /* @@@ I think stx should work to store */
+	st   %f2,  [ %sp + BIAS + 192 ]  /*     all 64bits, but I get "Illegal   */
+	st   %f3,  [ %sp + BIAS + 196 ]  /*     Operands", so using single prec. */
+	st   %f4,  [ %sp + BIAS + 200 ]  /*     store (st) */
+	st   %f5,  [ %sp + BIAS + 204 ]
+	st   %f6,  [ %sp + BIAS + 208 ]
+	st   %f7,  [ %sp + BIAS + 212 ]
+	st   %f8,  [ %sp + BIAS + 216 ]
+	st   %f9,  [ %sp + BIAS + 220 ]
+	st   %f10, [ %sp + BIAS + 224 ]
+	st   %f11, [ %sp + BIAS + 228 ]
+	st   %f12, [ %sp + BIAS + 232 ]
+	st   %f13, [ %sp + BIAS + 236 ]
+	st   %f14, [ %sp + BIAS + 240 ]
+	st   %f15, [ %sp + BIAS + 244 ]
+	st   %f16, [ %sp + BIAS + 248 ]
+	st   %f17, [ %sp + BIAS + 252 ]
+	st   %f18, [ %sp + BIAS + 256 ]
+	st   %f19, [ %sp + BIAS + 260 ]
+	st   %f20, [ %sp + BIAS + 264 ]
+	st   %f21, [ %sp + BIAS + 268 ]
+	st   %f22, [ %sp + BIAS + 272 ]
+	st   %f23, [ %sp + BIAS + 276 ]
+	st   %f24, [ %sp + BIAS + 280 ]
+	st   %f25, [ %sp + BIAS + 284 ]
+	st   %f26, [ %sp + BIAS + 288 ]
+	st   %f27, [ %sp + BIAS + 292 ]
+	st   %f28, [ %sp + BIAS + 296 ]
+	st   %f29, [ %sp + BIAS + 300 ]
+	st   %f30, [ %sp + BIAS + 304 ]
+	st   %f31, [ %sp + BIAS + 308 ]
+	stx  %g0,  [ %sp + BIAS + 312 ] /* init DCArg's i */
 
 	/* Zero retval store. */
-	stx  %g0, [ %sp + BIAS + 200 ]
+	stx  %g0, [ %sp + BIAS + 320 ]
 
 	/* Prepare callback handler call. */
 	mov  %g1, %o0                   /* Param 0 = DCCallback*, %g1 holds ptr to thunk */
-	add  %sp, BIAS + 192, %o1       /* Param 1 = DCArgs* (ptr to struct with args ptr) */
-	add  %sp, BIAS + 200, %o2       /* Param 2 = results ptr to 8b of local stack data */
+	add  %sp, BIAS + 176, %o1       /* Param 1 = DCArgs* (ptr to struct with args ptr) */
+	add  %sp, BIAS + 320, %o2       /* Param 2 = results ptr to 8b of local stack data */
 	ldx  [ %g1 + 64 ], %o3          /* Param 3 = userdata ptr */
 
 	/* Fetch callback handler address (after thunk blob) and call. */
@@ -70,8 +104,8 @@
 	nop
 
 	/* Put retval in %i0 (to be in caller's %o0), and %f0. */
-	ldx  [ %sp + BIAS + 200 ], %i0
-	ldd  [ %sp + BIAS + 200 ], %f0
+	ldx  [ %sp + BIAS + 320 ], %i0
+	ldd  [ %sp + BIAS + 320 ], %f0
 
 	/* Epilog. */
 	restore                 /* unshift reg window */