The MSTA instruction moves the contents of an even/odd pair of GPRs into the modifiable area of the current linkage stack entry. You might use the ESTA instruction later to load the contents of the modifiable area into registers.

In the following example, general registers 6 and 7 contain 8 bytes to be placed into the modifiable area of the current linkage stack entry. The MSTA instruction copies the 8 bytes to the modifiable area. The load address (LA) instruction loads a code of 3 into GPR 1. (The code for the modifiable area is "3".) Later in the example, the ESTA instruction copies the contents of the modifiable area into general register 2.

* Program entered through a stacking PC or BAKR
* General registers 6 and 7 contain 8 bytes to be placed
* into modifiable area of the current linkage stack entry
* Code of 3 identifies the modifiable area in entry
    .
    .
    MSTA 6        Update modifiable area
    .
    .
    LA   1,3      Load code of 3 into general register 1
    ESTA 2,1      Load modifiable area into general registers 2 and 3

For an example of using MSTA to pass data to an associated recovery routine (ARR), see the section on providing recovery in the z/OS MVS Programming: Authorized Assembler Services Guide.