With POCO, TLS is implemented as a class template, allowing one to use it with almost any type.

As detailed by the official documentation:

#include "Poco/Thread.h" 
#include "Poco/Runnable.h" 
#include "Poco/ThreadLocal.h" 
#include <iostream> 
 
class Counter: public Poco::Runnable { 
    void run() { 
        static Poco::ThreadLocal<int> tls; 
        for (*tls = 0; *tls < 10; ++(*tls)) { 
            std::cout << *tls << std::endl; 
        } 
    } 
}; 
 
int main(int argc, char** argv) { 
    Counter counter1; 
    Counter counter2; 
    Poco::Thread t1; 
    Poco::Thread t2; 
    t1.start(counter1); 
    t2.start(counter2); 
    t1.join(); 
    t2.join(); 
    return 0; 
} 

In this preceding worker example, we create a static TLS variable using the ThreadLocal class template, and define it to contain an integer.

Because we define it as static, it will only be created once per thread. In order to use our TLS variable, we can use either the arrow (->) or asterisk (*) operator to access its value. In this example, we increase the TLS value once per cycle of the for loop until the limit has been reached.

This example demonstrates that both threads will generate their own series of 10 integers, counting through the same numbers without affecting each other.