diff --git a/rtos/TARGET_CORTEX/TOOLCHAIN_ARM_MICRO/mbed_boot_arm_micro.c b/rtos/TARGET_CORTEX/TOOLCHAIN_ARM_MICRO/mbed_boot_arm_micro.c
index 06373232de..87a26477c7 100644
--- a/rtos/TARGET_CORTEX/TOOLCHAIN_ARM_MICRO/mbed_boot_arm_micro.c
+++ b/rtos/TARGET_CORTEX/TOOLCHAIN_ARM_MICRO/mbed_boot_arm_micro.c
@@ -20,14 +20,11 @@
 #include "mbed_boot.h"
 #include "mbed_assert.h"
 
-/* Symbols that are typically defined in startup_<mcu>.S */
-extern uint32_t __initial_sp[];
-extern uint32_t __heap_base[];
-extern uint32_t __heap_limit[];
+extern uint32_t               Image$$ARM_LIB_STACK$$ZI$$Base[];
+extern uint32_t               Image$$ARM_LIB_STACK$$ZI$$Length[];
 
-#if !defined(ISR_STACK_SIZE)
-#define ISR_STACK_SIZE ((uint32_t)1024)
-#endif
+extern uint32_t               Image$$ARM_LIB_HEAP$$ZI$$Base[];
+extern uint32_t               Image$$ARM_LIB_HEAP$$ZI$$Length[];
 
 /*
  * mbed entry point for the MICROLIB toolchain
@@ -41,12 +38,11 @@ void _main_init(void) __attribute__((section(".ARM.Collect$$$$000000FF")));
 void _main_init(void)
 {
     /* microlib only supports the two region memory model */
+    mbed_stack_isr_start = (unsigned char *) Image$$ARM_LIB_STACK$$ZI$$Base;
+    mbed_stack_isr_size = (uint32_t) Image$$ARM_LIB_STACK$$ZI$$Length;
 
-    mbed_heap_start = (unsigned char *)__heap_base;
-    mbed_heap_size = (uint32_t)__heap_base - (uint32_t)__heap_limit;
-
-    mbed_stack_isr_start = (unsigned char *)((uint32_t)__initial_sp - ISR_STACK_SIZE);
-    mbed_stack_isr_size = ISR_STACK_SIZE;
+    mbed_heap_start = (unsigned char *) Image$$ARM_LIB_HEAP$$ZI$$Base;
+    mbed_heap_size = (uint32_t) Image$$ARM_LIB_HEAP$$ZI$$Length;
 
     mbed_init();
     mbed_rtos_start();
diff --git a/targets/TARGET_WIZNET/TARGET_W7500x/TARGET_WIZwiki_W7500P/device/TOOLCHAIN_ARM_MICRO/W7500.sct b/targets/TARGET_WIZNET/TARGET_W7500x/TARGET_WIZwiki_W7500P/device/TOOLCHAIN_ARM_MICRO/W7500.sct
index f9ead04667..19589ce626 100644
--- a/targets/TARGET_WIZNET/TARGET_W7500x/TARGET_WIZwiki_W7500P/device/TOOLCHAIN_ARM_MICRO/W7500.sct
+++ b/targets/TARGET_WIZNET/TARGET_W7500x/TARGET_WIZwiki_W7500P/device/TOOLCHAIN_ARM_MICRO/W7500.sct
@@ -1,3 +1,11 @@
+#! armcc -E
+
+#if !defined(MBED_BOOT_STACK_SIZE)
+  #define MBED_BOOT_STACK_SIZE 0x400
+#endif
+
+#define Stack_Size MBED_BOOT_STACK_SIZE
+
 ; *************************************************************
 ; *** Scatter-Loading Description File generated by uVision ***
 ; *************************************************************
@@ -11,5 +19,9 @@ LR_IROM1 0x00000000 0x00020000  {    ; load region size_region
   RW_IRAM1 0x20000000 0x00004000  {  ; RW data
    .ANY (+RW +ZI)
   }
+  ARM_LIB_HEAP AlignExpr(+0, 16) EMPTY (0x20000000 + 0x00004000 - Stack_Size - AlignExpr(ImageLimit(RW_IRAM1), 16))  {
+  }
+  ARM_LIB_STACK (0x20000000+0x00004000) EMPTY -Stack_Size  { ; stack
+  }
 }
 
diff --git a/targets/TARGET_WIZNET/TARGET_W7500x/TARGET_WIZwiki_W7500P/device/TOOLCHAIN_ARM_MICRO/startup_W7500x.S b/targets/TARGET_WIZNET/TARGET_W7500x/TARGET_WIZwiki_W7500P/device/TOOLCHAIN_ARM_MICRO/startup_W7500x.S
index 124a5e65c8..5b161ed02e 100644
--- a/targets/TARGET_WIZNET/TARGET_W7500x/TARGET_WIZwiki_W7500P/device/TOOLCHAIN_ARM_MICRO/startup_W7500x.S
+++ b/targets/TARGET_WIZNET/TARGET_W7500x/TARGET_WIZwiki_W7500P/device/TOOLCHAIN_ARM_MICRO/startup_W7500x.S
@@ -27,29 +27,8 @@
 ;*/
 
 
-; <h> Stack Configuration
-;   <o> Stack Size (in Bytes) <0x0-0xFFFFFFFF:8>
-; </h>
-
-Stack_Size      EQU     0x00000400
-
-                AREA    STACK, NOINIT, READWRITE, ALIGN=3
-Stack_Mem       SPACE   Stack_Size
 __initial_sp    EQU     0x20004000 ; Top of RAM (16 KB for WIZwiki_W7500)
 
-
-; <h> Heap Configuration
-;   <o>  Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>
-; </h>
-
-Heap_Size       EQU     0x00000400
-
-                AREA    HEAP, NOINIT, READWRITE, ALIGN=3
-__heap_base
-Heap_Mem        SPACE   Heap_Size
-__heap_limit
-
-
                 PRESERVE8
                 THUMB
 
@@ -204,10 +183,4 @@ EXTI_Handler
 
 
                 ALIGN
-
-
-                EXPORT  __initial_sp
-                EXPORT  __heap_base
-                EXPORT  __heap_limit
-
                 END