PAK_CHECK_STOB is a standard SAP function module that performs functionality. This is available within standard R/3 SAP systems depending on version and release level.
Below are the pattern details for this FM showing its interface including any import, export and tables parameters. There is also a list of Exceptions and for your convenience any standard documentation available. All this information and more can also be viewed if you enter the function module name PAK_CHECK_STOB into the relevant SAP transaction such as SE37 or SE80.
CALL FUNCTION 'PAK_CHECK_STOB' "
EXPORTING
i_elem_key = " elemgenkey
IMPORTING
e_elem_exists = " flag
e_package_name = " devclass
. " PAK_CHECK_STOB