Retrieving The Estimated Window Size For pwelch Function

For learning purposes, I am trying to return the estimated window size value from the pwelch function.

I have a 500hz + 550hz computed sine wave with an fs = 50000 , N = 5000 .

With the function called:

[pw, window] = pwelch(x, [], [], [], fs);

My window variable is a 1025 length vector with low value doubles. If pwelch automatically segments x into 8 parts, why am I not seeing a scalar with the value of 625 (5000 / 8) ?