1. A computer-implemented method for batch evaluating a program instruction within a stack evaluator, the method comprising: generating a call frame associated with the program instruction within a call stack that is associated with a program subroutine which includes the program instruction, wherein the call frame includes one or more expressions specified by the program instruction; generating a child frame associated with a first expression of the one or more expressions within the call stack; initiating evaluation of the first expression associated with the child frame; automatically determining, in response to the initiating, whether the first expression associated with the child frame should be sent for batch processing by an application server based on a particular characteristic in common between the first expression and each of one or more other expressions; transitioning the call stack into blocked state, in response to determining that the first expression should be sent for batch processing by the application server; sending the first expression and each of the one or more other expressions to the application server; in response to the application server processing the first expression associated with the child frame, receiving a modification to the child frame that sets a value of the first expression within the child frame; unblocking the call stack; and evaluating the call frame based at least in part on the value of the first expression within the child frame.