The support costs of a system during the operational phase of its life-cycle represent a substantial part of the total life-cycle cost. Also, the support costs strongly depend on the decisions taken during the initial stages of the system design. However, traditionally many major systems have been developed attending only to the criteria deriving from the main functions of the system concerned. Questions related to logistic support were taken into account a posteriori, when the system was about to start the operational phase. Hence, the life-cycle costs were much bigger than initially foreseen, and at the same time, the maintenance and operation of the system suffered from inefficiency. This problem is further exacerbated as the complexity of the system increases. In the light of these considerations, it is obvious that the development of the Gran Telescopio Canarias (GTC) has to be considered as an integral concept that takes into account not only the scientific but also the logistic-support requirements. Such a compromise requires logistic support to be considered at all the phase of the life-cycle of the system, especially in those design stages in which the main decisions affecting the configuration of the system are taken. This paper presents the integrated logistic support (ILS) approach that will be followed to design the GTC in such a way as to make it effectively and economically supportable, as well as to develop the necessary elements for supporting it. A goal is to reach an optimum compromise between the cost of designing the GTC, including the support elements, and the cost of the support itself. Also, the logistic-support analysis will lead to the plan for the GTC operation and maintenance.