Gracious
Jasia is a diminutive form of Janina or Joanna, widely used in Poland. It shares the same etymological roots as Jane and Joan, ultimately deriving from the Hebrew name Yochanan. It represents a soft, feminine alternative to more common biblical derivatives.
Less common today
Jasia isn't in the latest US Top 1000. It last peaked at #3,965 in 2000.
US births per 5-year period, 1990βpresent (SSA data).