[ixp1200] Memory allocation problem

Hi, I need to implement a pattern matching algo(Aho Corasick) for my project, which requires a state machine build. And since this requires memory to be allocated dynamically which is not possible with IXP1200 (no Malloc), I defined a large array in SRAM to block certain memory for building the state machine. Though I specified the start location for this array, the memory getting assigned randomly and over writing some data( a large set of rules which need to be placed only in SRAM due to alignment problems). So can anyone pl.suggest me how I can block certain amount of memory in SRAM with an array and use it for my state machine without over writing. thanx in advance malathi