Oracle stored procedure - can I assign value to the variable in declaration block?

Oracle stored procedure - can I assign value to the variable in
declaration block?

I am writing a stored procedure in oracle and I would like to assign a
value to variable right from the start:
CREATE PROCEDURE proc
(
param1
, param2
)
AS
variable1 INT AS SELECT MAX(value) FROM table WHERE field = param1;
BEGIN
...
Is it allowed or should I do it in executable block?