nope, glowstone actually melts snow and ice at a greater range than torches do. Just put the torches a few blocks away from the snow/ice. But, the best source of light that wont melt the ice would be the sun.
Technically here are no light sources you can place that 'don't melt ice'. Lights in Minecraft are broken down into two types: the sun and everything else. If the placeable light source level is 12 or above, ice will melt.
Enemy mobs spawn at light level 7 or lower. The only light source weak enough to place near ice, redstone, only generates a light level of 7...so it won't be enough to prevent mob spawns. All other light sources are too bright to be placed directly by ice.
Redstone, as mentioned above, is neither bright enough to melt ice nor keep mobs away. However, mobs cannot spawn on translucent blocks (half-blocks, glass, ice, etc) and thus you may be able to get away with just redstone lights. If you have opaque blocks in your floor, you'll need to have some torches/fire/etc nearby.
However, having done a massive snowy non-legit (underwater) construction, I recommend Snow Blocks as a primary building material. They don't melt, even to lava, and snowblocks + glowstone + glass = wicked awesome. Especially when it's underwater.
I personally use lit netherrack to light my tundra and taiga biomes. The fire from them doesn't seem to melt the ice for some reason, even when the netherrack is set in the ground and surrounded by snow/ice.
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