The solubilities of both CaCO3 and Ca(OH)2 are, practically speaking, unlimited as long as acid is supplied. For example, consider hydrochloric:
CaCO3 + 2HCl ---> Ca++ + 2Cl- + CO2 + H2O
Ca(OH)2 + 2HCl --> Ca++ + 2Cl- +2H2O
The problem with calcium carbonate is thus not the solubility of chalk but the rate at which the reactions take place. It isn't that chalk doesn't dissolve - it's that it takes a long time to convert to bicarbonate thus upsetting the equilibrium at the particular pH so more chalk can dissolve. Thus one of the big problems with chalk is that it keeps dissolving long after we've made our pH checks. The pH keeps rising and rising until the wort is separated and the solid chalk removed. Given that the spreadsheets do not calculate the amount of chalk added to neutralize a given amount of acid correctly the slow kinematics are a mixed blessing. They protect one from overly high pH in the early parts of the mash but not the latter and one can go into the kettle with a higher pH than desired.
Just another reason not to use chalk in the mash. If you want to brew a beer that is normally made with carbonaceous water you must use carbonaceous water - not just throw chalk into the mash. In natural carbonaceous water the chalk is already dissolved by carbonic acid and you must do the same if you want the same mash/water chemistry that applied at the brewery whose beer you are trying to match. Problem is that it is a big PITA to do this but it can be done. Besides the pain brewers usually take steps to decarbonate their water so all the trouble you go to to carbonate it is a wasted effort.