diff --git a/src/ops/inc_multihead_self_attention.cu b/src/ops/inc_multihead_self_attention.cu
index c947d4ebef..25eda080ec 100644
--- a/src/ops/inc_multihead_self_attention.cu
+++ b/src/ops/inc_multihead_self_attention.cu
@@ -1116,41 +1116,47 @@ IncMultiHeadSelfAttentionMeta::IncMultiHeadSelfAttentionMeta(
         tokeninfo_size * sizeof(BatchConfig::PerTokenInfo) +
         complex_size * sizeof(cuFloatComplex); // more components will
                                                // be added here later
+    // memory can be shared across layers
+    size_t totalSharedSize =
+        infer_mode == TREE_VERIFY_MODE
+            ? totalSize -
+                  (key_cache_size + value_cache_size + qkv_max_proj_size) *
+                      size_of_dt
+            : totalSize - (key_cache_size + value_cache_size) * size_of_dt;
+    // memory can't be shared across layers.
+    size_t instance_size =
+        size_of_dt *
+        (infer_mode == TREE_VERIFY_MODE
+             ? key_cache_size + value_cache_size + qkv_max_proj_size
+             : key_cache_size + value_cache_size);
+
     if (offload) {
       // assert that we have enough reserved work space left
-      // memory can be shared across layers
-      size_t totalSharedSize =
-          infer_mode == TREE_VERIFY_MODE
-              ? totalSize -
-                    (key_cache_size + value_cache_size + qkv_max_proj_size) *
-                        size_of_dt
-              : totalSize - (key_cache_size + value_cache_size) * size_of_dt;
-      // memory can't be shared across layers.
-      size_t instance_size =
-          size_of_dt *
-          (infer_mode == TREE_VERIFY_MODE
-               ? key_cache_size + value_cache_size + qkv_max_proj_size
-               : key_cache_size + value_cache_size);
-
       if (quantization_type != DT_NONE) {
         totalSharedSize += quantized_weightSize;
       }
       assert(gpu_mem_allocator.reserved_total_size -
                  gpu_mem_allocator.reserved_allocated_size >=
              totalSharedSize);
-      gpu_mem_allocator.create_legion_instance(reserveInst, instance_size);
     } else {
-      gpu_mem_allocator.create_legion_instance(reserveInst, totalSize);
+      assert(handle.workSpaceSize >= totalSharedSize);
     }
 
-    // in tree_verify, enable devQKVProjArray;
-    if (!offload || infer_mode == TREE_VERIFY_MODE) {
+    gpu_mem_allocator.create_legion_instance(reserveInst, instance_size);
+    // workspace for shared memory across layers
+    char *work_space_start_ptr = (char *)handle.workSpace;
+
+    // QKV need to be persistent in Tree_kernel.
+    if (infer_mode == TREE_VERIFY_MODE) {
       devQKVProjArray = gpu_mem_allocator.allocate_instance_untyped(
           qkv_max_proj_size * size_of_dt);
-    } else {
+    } else if (offload) {
       devQKVProjArray = gpu_mem_allocator.allocate_reserved_untyped(
           qkv_max_proj_size * size_of_dt);
-      // offset += qkv_max_proj_size * size_of_dt;
+    } else {
+      // spec/inc + non-offload
+      devQKVProjArray = work_space_start_ptr;
+      work_space_start_ptr += qkv_max_proj_size * size_of_dt;
     }
 
     // use key value cache in all mode.
@@ -1177,17 +1183,19 @@ IncMultiHeadSelfAttentionMeta::IncMultiHeadSelfAttentionMeta(
           gpu_mem_allocator.allocate_reserved<cuFloatComplex>(complex_size);
       // offset += complex_size * sizeof(cuFloatComplex);
     } else {
-      token_infos =
-          gpu_mem_allocator.allocate_instance<BatchConfig::PerTokenInfo>(
-              tokeninfo_size);
-      qk_prods = gpu_mem_allocator.allocate_instance_untyped(qk_prod_size *
-                                                             size_of_dt);
-      qk_prods_softmax = gpu_mem_allocator.allocate_instance_untyped(
-          qk_prod_size * size_of_dt);
-      attn_heads = gpu_mem_allocator.allocate_instance_untyped(attn_heads_size *
-                                                               size_of_dt);
+      token_infos = static_cast<BatchConfig::PerTokenInfo *>(
+          (void *)work_space_start_ptr);
+      work_space_start_ptr +=
+          sizeof(BatchConfig::PerTokenInfo) * tokeninfo_size;
+      qk_prods = work_space_start_ptr;
+      work_space_start_ptr += qk_prod_size * size_of_dt;
+      qk_prods_softmax = work_space_start_ptr;
+      work_space_start_ptr += qk_prod_size * size_of_dt;
+      attn_heads = work_space_start_ptr;
+      work_space_start_ptr += attn_heads_size * size_of_dt;
       complex_input =
-          gpu_mem_allocator.allocate_instance<cuFloatComplex>(complex_size);
+          static_cast<cuFloatComplex *>((void *)work_space_start_ptr);
+      work_space_start_ptr += sizeof(cuFloatComplex) * complex_size;
     }
 
     // allocate more size for quantization data