BOOST_COMPUTE_CLOSURE triggers run-time compiling every time the closure value changes

Just wondering if this is a bug or a user error. The below is a snippet showing the issue. Trying to pass different run-time value to closure, that triggers the run-time compiling every time the transform() is called.

If this is user error or not supported, is there a workaround for supplying run-time values to algorithms?

boost::compute::device gpu =
boost::compute::system::default_device();

boost::compute::context context(gpu);

boost::compute::command_queue queue(context, gpu);

size_t size = 10000;
boost::compute::vector va(size, 1, queue);
boost::compute::vector vb(size, 2, queue);
boost::compute::vector vc(size, context);

size_t N = 100;
for (size_t i = 0; i < N-1; ++i)
{
int e = static_cast(i); // changing the 'e' here causing the transform() to compile every time is invoked

BOOST_COMPUTE_CLOSURE(int, calc, (int a, int b), (e),
{
return a + b + e;
});

boost::compute::transform(
va.begin(),
va.end(),
vb.begin(),
vc.begin(),
calc,
queue);
}

Cheers