Held in abeyance; reserved to be dealt with later; on hold, on the back burner: The plan's in cold storage for now/ Well, let's just keep that one in the deep freeze for a few months(1940s+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with in cold storage
In a state of abeyance or postponement. For example, We can't consider these design changes now; let's put them in cold storage for a year or so. This expression alludes to the literal storage of food, furs, or other objects in a refrigerated place.
[ ; late 1800s