Use the Threaded Server Stack(-threadedServerStack) parameter to specify the size of a stack allocated for each thread spawned by a threaded server.

Operating system and syntax UNIX / Windows 
-threadedServerStack n
Use with Maximum value Minimum value Single-user default Multi-user default
Database Server 2147483647 64 — 512
n
Indicates the size, in Kb, of a stack reserved for each thread of a threaded server.

The -threadedServerStack parameter is specified for each broker, and can not be changed at run time.