diff --git a/src/crystal/system/thread_local.cr b/src/crystal/system/thread_local.cr
index fa651de00997..19333bbafd40 100644
--- a/src/crystal/system/thread_local.cr
+++ b/src/crystal/system/thread_local.cr
@@ -1,20 +1,20 @@
 class Thread
   struct Local(T)
     # Reserves space for saving a `T` reference on each thread.
-    def initialize
-      {% unless T < Reference || T < Pointer || T.union_types.all? { |t| t == Nil || t < Reference } %}
-        {% raise "Can only create Thread::Local with reference types, nilable reference types, or pointer types, not {{T}}" %}
-      {% end %}
-    end
+    # def self.new
+    #   {% unless T < Reference || T < Pointer || T.union_types.all? { |t| t == Nil || t < Reference } %}
+    #     {% raise "Can only create Thread::Local with reference types, nilable reference types, or pointer types, not {{T}}" %}
+    #   {% end %}
+    # end
 
     # Reserves space for saving a `T` reference on each thread and registers a
     # destructor that will be called when a thread terminates if the local value
     # has been set.
-    def initialize(&destructor : Proc(T, Nil))
-      {% unless T < Reference || T < Pointer || T.union_types.all? { |t| t == Nil || t < Reference } %}
-        {% raise "Can only create Thread::Local with reference types, nilable reference types, or pointer types, not {{T}}" %}
-      {% end %}
-    end
+    # def self.new(&destructor : Proc(T, Nil))
+    #   {% unless T < Reference || T < Pointer || T.union_types.all? { |t| t == Nil || t < Reference } %}
+    #     {% raise "Can only create Thread::Local with reference types, nilable reference types, or pointer types, not {{T}}" %}
+    #   {% end %}
+    # end
 
     # Returns the current local value for the thread; if unset constructs one by
     # yielding and sets it as the current local value.
diff --git a/src/crystal/system/unix/thread_local.cr b/src/crystal/system/unix/thread_local.cr
index 92eeaa5a9437..b7041a55b5b2 100644
--- a/src/crystal/system/unix/thread_local.cr
+++ b/src/crystal/system/unix/thread_local.cr
@@ -2,22 +2,22 @@ require "c/pthread"
 
 class Thread
   struct Local(T)
-    @key = uninitialized LibC::PthreadKeyT
-
-    def initialize
-      previous_def
-      @key = pthread_key_create(nil)
+    def self.new : self
+      err = LibC.pthread_key_create(out key, nil)
+      raise RuntimeError.from_os_error("pthread_key_create", Errno.new(err)) unless err == 0
+      new(key)
     end
 
-    def initialize(&destructor : Proc(T, Nil))
-      previous_def(&destructor)
-      @key = pthread_key_create(destructor.unsafe_as(Proc(Void*, Nil)))
+    def self.new(&destructor : Proc(T, Nil)) : self
+      err = LibC.pthread_key_create(out key, destructor.unsafe_as(Proc(Void*, Nil)))
+      raise RuntimeError.from_os_error("pthread_key_create", Errno.new(err)) unless err == 0
+      new(key)
     end
 
-    private def pthread_key_create(destructor)
-      err = LibC.pthread_key_create(out key, destructor)
-      raise RuntimeError.from_os_error("pthread_key_create", Errno.new(err)) unless err == 0
-      key
+    def initialize(@key : LibC::PthreadKeyT)
+      {% unless T < Reference || T < Pointer || T.union_types.all? { |t| t == Nil || t < Reference } %}
+        {% raise "Can only create Thread::Local with reference types, nilable reference types, or pointer types, not {{T}}" %}
+      {% end %}
     end
 
     def get? : T?
diff --git a/src/crystal/system/wasi/thread_local.cr b/src/crystal/system/wasi/thread_local.cr
index c03997493626..4de4edc3170c 100644
--- a/src/crystal/system/wasi/thread_local.cr
+++ b/src/crystal/system/wasi/thread_local.cr
@@ -2,12 +2,14 @@ class Thread
   struct Local(T)
     @value : T?
 
-    def initialize
-      previous_def
+    def self.new(&destructor : T ->) : self
+      new
     end
 
-    def initialize(&destructor : T ->)
-      previous_def(&destructor)
+    def initialize
+      {% unless T < Reference || T < Pointer || T.union_types.all? { |t| t == Nil || t < Reference } %}
+        {% raise "Can only create Thread::Local with reference types, nilable reference types, or pointer types, not {{T}}" %}
+      {% end %}
     end
 
     def get? : T?
diff --git a/src/crystal/system/win32/thread_local.cr b/src/crystal/system/win32/thread_local.cr
index e98e8a9f7267..aa417ae820ba 100644
--- a/src/crystal/system/win32/thread_local.cr
+++ b/src/crystal/system/win32/thread_local.cr
@@ -2,22 +2,22 @@ require "c/fibersapi"
 
 class Thread
   struct Local(T)
-    @key = uninitialized LibC::DWORD
-
-    def initialize
-      previous_def
-      @key = fls_alloc(nil)
+    def self.new : self
+      key = LibC.FlsAlloc(nil)
+      raise RuntimeError.from_winerror("FlsAlloc: out of indexes") if key == LibC::FLS_OUT_OF_INDEXES
+      new(key)
     end
 
-    def initialize(&destructor : Proc(T, Nil))
-      previous_def(&destructor)
-      @key = fls_alloc(destructor.unsafe_as(LibC::FLS_CALLBACK_FUNCTION))
+    def self.new(&destructor : Proc(T, Nil))
+      key = LibC.FlsAlloc(destructor.unsafe_as(LibC::FLS_CALLBACK_FUNCTION))
+      raise RuntimeError.from_winerror("FlsAlloc: out of indexes") if key == LibC::FLS_OUT_OF_INDEXES
+      new(key)
     end
 
-    private def fls_alloc(destructor)
-      key = LibC.FlsAlloc(destructor)
-      raise RuntimeError.from_winerror("FlsAlloc: out of indexes") if key == LibC::FLS_OUT_OF_INDEXES
-      key
+    def initialize(@key : LibC::DWORD)
+      {% unless T < Reference || T < Pointer || T.union_types.all? { |t| t == Nil || t < Reference } %}
+        {% raise "Can only create Thread::Local with reference types, nilable reference types, or pointer types, not {{T}}" %}
+      {% end %}
     end
 
     def get? : T?
diff --git a/src/regex/lib_pcre2.cr b/src/regex/lib_pcre2.cr
index 6f45a4465219..f6234e30b3c1 100644
--- a/src/regex/lib_pcre2.cr
+++ b/src/regex/lib_pcre2.cr
@@ -264,10 +264,12 @@ lib LibPCRE2
 
   fun jit_stack_create = pcre2_jit_stack_create_8(startsize : LibC::SizeT, maxsize : LibC::SizeT, gcontext : GeneralContext*) : JITStack*
   fun jit_stack_assign = pcre2_jit_stack_assign_8(mcontext : MatchContext*, callable_function : Void* -> JITStack*, callable_data : Void*) : Void
+  fun jit_stack_free = pcre2_jit_stack_free_8(jit_stack : JITStack*) : Void
 
   fun pattern_info = pcre2_pattern_info_8(code : Code*, what : UInt32, where : Void*) : Int
 
   fun match = pcre2_match_8(code : Code*, subject : UInt8*, length : LibC::SizeT, startoffset : LibC::SizeT, options : UInt32, match_data : MatchData*, mcontext : MatchContext*) : Int
+  fun match_data_create = pcre2_match_data_create_8(ovecsize : UInt32, gcontext : GeneralContext*) : MatchData*
   fun match_data_create_from_pattern = pcre2_match_data_create_from_pattern_8(code : Code*, gcontext : GeneralContext*) : MatchData*
   fun match_data_free = pcre2_match_data_free_8(match_data : MatchData*) : Void
 
diff --git a/src/regex/pcre2.cr b/src/regex/pcre2.cr
index b56a4ea68839..ca29dd38f46f 100644
--- a/src/regex/pcre2.cr
+++ b/src/regex/pcre2.cr
@@ -1,5 +1,5 @@
 require "./lib_pcre2"
-require "crystal/thread_local_value"
+require "crystal/system/thread_local"
 
 # :nodoc:
 module Regex::PCRE2
@@ -207,12 +207,14 @@ module Regex::PCRE2
   private def match_impl(str, byte_index, options)
     match_data = match_data(str, byte_index, options) || return
 
-    ovector_count = LibPCRE2.get_ovector_count(match_data)
+    # we reuse the same matchdata allocation, so we must "reimplement" the
+    # behavior of pcre2_match_data_create_from_pattern (get_ovector_count always
+    # returns 65535, aka the maximum):
+    ovector_count = capture_count_impl &+ 1
     ovector = Slice.new(LibPCRE2.get_ovector_pointer(match_data), ovector_count &* 2)
 
     # We need to dup the ovector because `match_data` is re-used for subsequent
-    # matches (see `@match_data`).
-    # Dup brings the ovector data into the realm of the GC.
+    # matches. Dup brings the ovector data into the realm of the GC.
     ovector = ovector.dup
 
     ::Regex::MatchData.new(self, @re, str, byte_index, ovector.to_unsafe, ovector_count.to_i32 &- 1)
@@ -228,43 +230,52 @@ module Regex::PCRE2
 
   class_getter match_context : LibPCRE2::MatchContext* do
     match_context = LibPCRE2.match_context_create(nil)
-    LibPCRE2.jit_stack_assign(match_context, ->(_data) { Regex::PCRE2.jit_stack }, nil)
+    LibPCRE2.jit_stack_assign(match_context, ->(_data) { current_jit_stack }, nil)
     match_context
   end
 
-  # Returns a JIT stack that's shared in the current thread.
+  # JIT stack is unique per thread.
   #
-  # Only a single `match` function can run per thread at any given time, so there
-  # can't be any concurrent access to the JIT stack.
-  @@jit_stack = Crystal::ThreadLocalValue(LibPCRE2::JITStack*).new
+  # Only a single `match` function can run per thread at any given time, so
+  # there can't be any concurrent access to the JIT stack.
+  protected class_getter(jit_stack) do
+    Thread::Local(LibPCRE2::JITStack*).new do |jit_stack|
+      LibPCRE2.jit_stack_free(jit_stack)
+    end
+  end
 
-  def self.jit_stack
-    @@jit_stack.get do
+  protected def self.current_jit_stack
+    jit_stack.get do
       LibPCRE2.jit_stack_create(32_768, 1_048_576, nil) || raise "Error allocating JIT stack"
     end
   end
 
-  # Match data is shared per instance and thread.
+  # Match data is unique per thread.
   #
-  # Match data contains a buffer for backtracking when matching in interpreted mode (non-JIT).
-  # This buffer is heap-allocated and should be re-used for subsequent matches.
-  @match_data = Crystal::ThreadLocalValue(LibPCRE2::MatchData*).new
+  # Match data contains a buffer for backtracking when matching in interpreted
+  # mode (non-JIT). This buffer is heap-allocated and should be re-used for
+  # subsequent matches.
+  protected class_getter(match_data) do
+    Thread::Local(LibPCRE2::MatchData*).new do |match_data|
+      LibPCRE2.match_data_free(match_data)
+    end
+  end
 
-  private def match_data
-    @match_data.get do
-      LibPCRE2.match_data_create_from_pattern(@re, nil)
+  protected def self.current_match_data : LibPCRE2::MatchData*
+    match_data.get do
+      # the ovector size is clamped to 65535 pairs; we declare the maximum
+      # because we allocate the match data buffer once for the thread and need
+      # to adapt to any regular expression
+      LibPCRE2.match_data_create(65_535, nil)
     end
   end
 
   def finalize
-    @match_data.consume_each do |match_data|
-      LibPCRE2.match_data_free(match_data)
-    end
     LibPCRE2.code_free @re
   end
 
   private def match_data(str, byte_index, options)
-    match_data = self.match_data
+    match_data = Regex::PCRE2.current_match_data
     match_count = LibPCRE2.match(@re, str, str.bytesize, byte_index, pcre2_match_options(options), match_data, PCRE2.match_context)
 
     if match_count < 0