POD initialization

I have the following structs below.

static PinDelayPtr unspecifiedPipoDelayModel(new PinDelay());

#define DELAY_VALUE_NOT_GIVEN -7654321.0

typedef boost::shared_ptr<struct PinDelay> PinDelayPtr

struct DelayTime
{
  double rise;
  double fall;

  DelayTime();
  DelayTime(const double r, const double f);
};

struct PinDelay
{
  DelayTime block;
  DelayTime drive;
  double load;
  double maxload;
  DelayTime usertime;

  PinDelay();

  PinDelay::PinDelay(const double pload, const double pmaxload,
                     const double brise, const double frise,
                     const double bfall, const double ffall,
                     const double urise, const double ufall);
};

struct DelayWireLoadTable
{
  double slope;
  unsigned int npinset;
  std::vector<double> pins;
};

struct DelayCircuitImpl
{
  DelayTime defarr;
  DelayTime defreq;
  DelayWireLoadTable wltable;
  PinDelayPtr pipomodel;
};

My constructors looks like the following:

DelayTime::DelayTime()
  : rise(DELAY_VALUE_NOT_GIVEN), fall(DELAY_VALUE_NOT_GIVEN) {}

PinDelay::PinDelay()
  : load(DELAY_VALUE_NOT_GIVEN), maxload(DELAY_VALUE_NOT_GIVEN) {}

DelayCircuit::DelayCircuit()
  : dc(new DelayCircuitImpl())
{
  dc->wltable.slope = DELAY_VALUE_NOT_GIVEN;
  dc->pipomodel = PinDelayPtr(new
PinDelay(*unspecifiedPipoDelayModel));
}

Since the struct contain POD (plain old data), I would think they
should be initialized to 0. However, I am not sure why the variable
'npinset' does not get a default value of 0. In my gdb output, I have
the following:
gdb) p *(*dc).dc
$4 = {
  defarr = {
    rise = -7654321,
    fall = -7654321
  },
  defreq = {
    rise = -7654321,
    fall = -7654321
  },
  wltable = {
    slope = -7654321,
    npinset = 6311712,
    pins = {
      <std::_Vector_base<double,std::allocator<double> >> = {
        _M_impl = {
          <std::allocator<double>> = {
            <__gnu_cxx::new_allocator<double>> = {<No data fields>},
<No data fields>},
          members of std::_Vector_base<double,std::allocator<double>


          _M_start = 0x0,
          _M_finish = 0x0,
          _M_end_of_storage = 0x0
        }
      }, <No data fields>}
  },
  pipomodel = {
    px = 0x602960,
    pn = {
      pi_ = 0x6029b0
    }
  }
}

Everything looks good except, npinset has a garbage value. Is there
something I am not understanding about POD initialization? Something
in my code that is preventing npinset to be initialized to 0? Any
clarification is appreciation.

Thanks for your time.