RTEMS now provides a mechanism for interrogating the memory allocator.

src/libCom/osi/os/RTEMS/osdPoolStatus.c

@@ -0,0 +1,12 @@
+#include <rtems/libcsupport.h>
+
+#define epicsExportSharedSymbols
+#include "osiPoolStatus.h"
+
+/*
+ * osiSufficentSpaceInPool ()
+ */
+epicsShareFunc int epicsShareAPI osiSufficentSpaceInPool ()
+{
+    return (malloc_free_space() > 100000);
+}