Issue #24952: Clarify default argument of stack_size() in threading, _thread

Patch from Mattip.

Doc/library/_thread.rst

@@ -93,7 +93,8 @@ It defines the following constants and functions:
    Return the thread stack size used when creating new threads.  The optional
    *size* argument specifies the stack size to be used for subsequently created
    threads, and must be 0 (use platform or configured default) or a positive
-   integer value of at least 32,768 (32 KiB). If changing the thread stack size is
+   integer value of at least 32,768 (32 KiB). If *size* is not specified,
+   0 is used.  If changing the thread stack size is
    unsupported, a :exc:`RuntimeError` is raised.  If the specified stack size is
    invalid, a :exc:`ValueError` is raised and the stack size is unmodified.  32 KiB
    is currently the minimum supported stack size value to guarantee sufficient

Doc/library/threading.rst

@@ -89,7 +89,8 @@ This module defines the following functions:
    Return the thread stack size used when creating new threads.  The optional
    *size* argument specifies the stack size to be used for subsequently created
    threads, and must be 0 (use platform or configured default) or a positive
-   integer value of at least 32,768 (32 KiB). If changing the thread stack size is
+   integer value of at least 32,768 (32 KiB). If *size* is not specified,
+   0 is used.  If changing the thread stack size is
    unsupported, a :exc:`RuntimeError` is raised.  If the specified stack size is
    invalid, a :exc:`ValueError` is raised and the stack size is unmodified.  32 KiB
    is currently the minimum supported stack size value to guarantee sufficient

Misc/ACKS

@@ -888,6 +888,7 @@ Nick Mathewson
 Simon Mathieu
 Laura Matson
 Graham Matthews
+mattip
 Martin Matusiak
 Dieter Maurer
 Daniel May

Misc/NEWS

@@ -456,6 +456,9 @@ C API
 Documentation
 -------------
 
+- Issue #24952: Clarify the default size argument of stack_size() in
+  the "threading" and "_thread" modules. Patch from Mattip.
+
 - Issue #24808: Update the types of some PyTypeObject fields. Patch by
   Joseph Weston.