The ornamental design for a garmentwaistband, as shown and described.
FIG. 1 is a perspective view of a garment waistband showing my new design;
FIG. 2 is a front view of the garment waistband;
FIG. 3 is an enlarged view of area 3 of FIG. 2;
FIG. 4 is a rear view of the garment waistband;
FIG. 5 is a side view of the garment waistband, the opposing side view being a mirror image; and,
FIG. 6 is a perspective view of the garment waistband in an alternate configuration.
The long and short broken lines represent the bounds of the claimed design and form no part thereof; the evenly spaced broken lines show portions that form no part of the claimed design. The stippling pattern represents a first fabric. The crosshatched pattern represents a second fabric having different visual characteristics from the first fabric.